Abstract:
A substantially transparent separator for separating fish or other aquatic animals within a water-filled display tank is disclosed. The separator divides the tank into multiple, fully viewable regions in fluid communication with each other. The separator comprises at least one transparent, hollow transit chamber, which has opposing mouth openings cut through its surface. Affixed to each of the mouth openings are rigid, substantially vertical divider plates. Apertures through the divider plates adjoin the mouth openings of the transit chamber(s) to form a protected aquatic passageway through the interior of the tank. The separator thus allows groups of physically separated fish or other aquatic animals to swim above, beneath, and beside each other in a three-dimensional manner. Also, each group of aquatic animals has access to the water surface for feeding. The separator of the present invention is further improved by the addition of guide rails and isolator plates, which permit removal of the separator for cleaning while maintaining separation between the various groups of fish or other animals.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 09/969,465 filed Oct. 2, 2001, now U.S. Pat. No. 6,443,099. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to aquatic animal culturing and display, and particularly to improvements in dividers or separator assemblies used to separate fish within an ornamental fish display tank or aquarium. The breeding and display of live fish within transparent tanks or aquariums is a popular way to add beauty, color, and movement to a home or office. To achieve a varied and interesting aquarium scene, aquarium hobbyists often prefer to display fish of different breeds, sizes and shapes within the same tank. They also typically provide ornaments, obstacles, and decorative backgrounds within the tanks. This variation of fish type and environment adds to the enjoyment of viewers, who are able to see varied types of fish swimming above, below, over and around both each other and the tank ornaments in a rich three-dimensional environment. 
     A known drawback to displaying fish of various sizes in the same tank is the natural tendency of larger fish to eat smaller fish. This is particularly a problem when newly hatched baby fish, or fry, are contained within the same tank as the mother fish and other larger fish. In such cases, the mother and/or the other larger fish will tend to cannibalize the fly. Also, certain types of fish are known to have aggressive tendencies and will attack other fish, injuring or killing them. For the tropical fish hobbyist, who may have spent large amounts of time and money acquiring and breeding fish, having prized pets devour or maim one another is undesirable. Fish hobbyists have therefore sought ways to keep hostile fish physically separate from other more docile fish while maintaining an interesting live display. 
     A number of potential solutions to the problem of separating incompatible fish within display tanks have arisen. These approaches include placing screens, panels, and or perforated boxes or cylinders within the tank to divide it into separate compartments. Unfortunately, use of such devices often restrict the movement and of the fish such that they can no longer swim above, below and around each other in a fully three-dimensional manner. Likewise, if opaque structures are used as tank dividers, they limit the permissible angles, areas, and opportunities for viewing the fish, which again detracts from the three-dimensional appearance of the aquatic environment. In addition, if the separator structure creates a completely enclosed compartment with a sealed top, the fish within it will not have access to the water surface, which is important for feeding. Furthermore, these systems often require that the divider elements themselves be mounted to the walls of the fish tank, making initial installation and removal for cleaning difficult. Also, many structures create a substantially watertight seal between the separated compartments, making it necessary to use multiple air pump units for oxygenating the water within each compartment. These shortcomings are addressed by the present invention. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a transparent separator for use within a fish display tank that separates the tank into multiple, fully viewable compartments, or “aquatic regions,” which are.in fluid communication with each other. A first group of fish (eg., hostile fish) confined within one of the aquatic regions is able to “visibly,” swim through areas that are surrounded by the aquatic region occupied by other (e.g., small or docile) fish, while remaining physically separated from those fish. The separator system disclosed thus allows groups of separated fish to swim above, beneath, beside, and around each other in a fully three-dimensional manner. 
     In accordance with the present invention, the separator comprises at least one rigid, transparent, hollow transit chamber, which has opposing mouth openings cut through its surface. Securely affixed to each of the mouth openings are rigid, transparent divider plates, which are oriented substantially vertically. Apertures are cut through the divider plates adjacent to and in correspondence with the mouth openings of the attached transit chamber(s). Thus, each transit chamber provides, a passageway through the separator that extends through the aperture of one divider plate, into the intervening transit chamber, and finally out through the opposite aperture of the other divider plate. The divider plates are oriented symmetrically to one another and are rigidly affixed to the transit chamber. The divider plates are sized such that when the separator is placed within a fish tank (with the transit chamber submerged beneath the tank&#39;s surface water level, and with the inner volume of the transit chamber filled with water), the divider plates rest stably on the floor of the tank. The top surfaces of the divider plates extend slightly above the surface water level of the tank. The outer dimensions of the separator assembly are smaller than the inner dimensions of the fish display tank so that the separator easily fits within the display tank. 
     The symmetrically disposed divider plate or plates may be positioned such that less than all sides, excluding the top and bottom sides, of at least one transit chamber are surrounded by the divider plate assembly. In this case, the side edges of the divider plates are either positioned adjacent to the inner surfaces of the fish display tank, or the side edges are positioned adjacent to the side edge region of a neighboring divider plate. Whenever a side edge of a divider plate is positioned adjacent to either an inner surface of the fish display tank or the side edge region of a neighboring divider plate, the spacing between that side edge and the adjacent surface must be such that fish (or any other preferred aquatic animal) larger than a selected size cannot pass through any gap formed at this boundary. Thus, the selected fish are confined to one aquatic region since they cannot pass from an aquatic region whose boundary includes the inner surface of one divider plate to an aquatic region whose boundary includes the outer surface of that same divider plate, or vice versa. The separator therefore effectively divides the fish display tank into plural aquatic regions, each of which have access to the water surface. 
     In cases where a divider plate&#39;s side edges are adjacent a neighboring divider plate, those plates may be integrally connected, in which case, there would be no effective boundary gap. For purposes of the present invention, divider plates, or divider plate/transit chamber assemblies are considered to be “integrally connected” when they are molded from a single piece of material, or are adhesively affixed together, or are connected by permanent solid or perforated edge connectors (the latter being adequate so long as the dimensions of any perforations are sufficiently small that fish larger than a selected size cannot pass through them). 
     The “selected size” of the confined fish will vary depending on the relative sizes of the fish that are to be segregated. If the segregation of fish is to be completely mutual, such as when one chooses to confine fish of different breeds or appearances or temperaments to different aquatic regions, the selected size of the fish should be such that even the smallest of these fish cannot pass through the boundary gaps. 
     In one alternative embodiment, symmetrically disposed divider plate or plates are positioned such that all sides, excluding the top and bottom, of at least one transit chamber are completely surrounded by the divider plate assembly. In this configuration, the divider plates may be integrally connected, or the side edges of non-integrally connected divider plates should be positioned sufficiently close to the side edges of adjacent neighboring divider plates that fish larger than a selected size cannot pass through the boundary gaps. Thus, in this configuration, as with the others, fish larger than a selected size cannot pass from the aquatic region whose boundary includes the inner (outer) surface of a divider plate to an aquatic region whose boundary includes the outer (inner) surface of that same divider plate. 
     In an alternative construction, a separator of the present invention is further improved by the addition of a set of guide rails and isolator plates that permit removal of the separator for cleaning while maintaining separation between the various groups of fish. These components facilitate removal of the separator by permitting the separator to be removed while nevertheless maintaining separation of the various groups of fish. Thus, with these components, the separator may be removed for purposes such as cleaning without requiring removal of any of the fish. In addition, these components promote the stability of the separator without relying on its symmetrical structure. 
     Many different shapes and configurations of separator components are possible within the scope of the present invention. These and other advantages and features of the present invention will become apparent from consideration of the attached drawings and the detailed description. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a perspective view of a separator in accordance with the present invention. 
     FIG. 2 is a front elevation view of the separator assembly of FIG.  1 . 
     FIG. 3 is a side elevation view of the separator assembly of FIG.  1 . 
     FIG. 4 is a side elevation view of an alternative feature of the embodiment of FIG.  1 . 
     FIG. 5 a  is a partial view depicting components of a separable joint assembly for use with the present invention, with the components unattached. 
     FIG. 5 b  is a partial view depicting components of a separable joint assembly for use with the present invention, with the components attached. 
     FIG. 5 c  is a partial exploded view depicting components of the separable joint assembly. 
     FIG. 5 d  is a sectional view of FIG. 5 a  taken along the line B—B′. 
     FIG. 6 is a perspective view of an alternative embodiment of the separator assembly. 
     FIG. 7 is a perspective view of another alternative embodiment of the separator assembly. 
     FIG. 8 is a perspective view of another alternative embodiment of the separator assembly. 
     FIG. 9 a  is a perspective view of another alternative embodiment of the separator assembly. 
     FIG. 9 b  is a partial view depicting an alternative feature of the embodiment of FIG. 9 a.    
     FIG. 10 is a perspective view of another alternative embodiment of the separator assembly. 
     FIG. 11 is an exploded view of the separator assembly of the present invention, which has been further improved by the addition of a set of guide rails and isolator plates. 
     FIG. 12 is a perspective view of the separator assembly of the present invention with the addition of a set of guide rails and isolator plates. 
     FIG. 13 is a partial top down planar view of a guide rail for use with the separator assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A separator for a fish display tank in accordance with the present invention is depicted in FIG.  1 . In FIG. 1, the separator  10  of the present invention includes divider plates  20  and  25 , which are substantially planar and are oriented substantially vertically, (i.e, they rest on a bottom edge as opposed to a planar face). These divider plates are securely and rigidly connected to the mouth openings of a tubular transit chamber  30 . The divider plates  20  and  25  have apertures therethrough which are positioned adjacent to and in correspondence with the openings at the ends of transit chamber  30 . The separator assembly is contained within fish display tank  100 , which has bottom surface  70 , front and rear inner surfaces  75 , and left and right inner surfaces  77 . The display tank  100  is filled with water having a surface water level  150 . The divider plates  20  and  25  each have top, bottom, and front and rear side surfaces. With respect to divider plate  20 , the top surface is identified as  20   a , the bottom surface as  20   d , rear side surface as  20   b , and front side surface as  20   c . The corresponding surfaces of plate  25  are not labeled. The divider plate  20  has a width such that front side surface  20   c  and rear side surface  20   b  are adjacent to, though not necessarily in contact with,.the inner side surfaces  75  of the fish display tank. The side surfaces of plate  25  are similarly disposed. In addition, the divider plates  20  and  25  are of such a height, and the display tank  100  contains a sufficient volume of water, such that the tops of plates  20  and  25  extend slightly above surface water level  150 . Thus, the separator assembly  10  effectively partitions the inner volume of display tank  100  into two aquatic regions,  110  and  115 . 
     Regions  110  and  115  are more easily seen in FIG. 2, which is an elevation view from the front of the fish display tank. The aquatic region  110  is bounded by the left and right inner surfaces  77  of the fish display tank, the outer surface  27  of divider plate  25 , the outer surface  22  of divider plate  20 , and the inner surface  32  of the transit chamber  30 . The aquatic region  110  therefore also includes the passageway  120 , which extends through the interior of the transit chamber  30  and out the corresponding apertures in divider plates  20  and  25 . The aquatic region  115  is bounded by the inner surface  26  of divider plate  25 , the inner surface  21  of divider plate  20 , and the outer surface  34  of transit chamber  30 . The aquatic region  115  therefore completely surrounds the outer surface of transit chamber  30 , but is separated from the interior of chamber  30 . From the line A 1  in FIG.2, which bisects transit chamber  30 , it can also be seen that divider plates  20  and  25  are symmetrically disposed about the transit chamber with one plate at either end. Since the plates  20  and  25  are also rigidly connected to the mouth openings of transit chamber  30 , the separator assembly will rest stably on the bottom surface  70  of fish display tank  100  without the need for attaching the assembly to the walls of the fish display tank. This stability is particularly promoted when passageway  120  within the transit chamber  30  is completely filled with water. Furthermore, it is to be noted that the separator assembly configuration leaves portions of both aquatic region  110  and aquatic region  115  open to the water surface, allowing any fish in these regions to have access to the water surface for feeding. 
     The transit chamber of the separator assembly  10  should be formed from a generally rigid, transparent material, and preferably the divider plates should be as well. Transparent here means that the material should transmit light sufficiently such that fish within the display tank can still be seen when both a wall of the display tank and a surface of the separator assembly are between the fish and the viewer&#39;s line of sight. Such transparent materials include crystal, glass, plastics, acrylics, and other suitable polymers or hard resins. 
     Referring again to FIG. 1, aquatic region  115  of the display tank  100  is populated by fish  200  while fish  250  are located within the aquatic region  110 . If for example, it is desired to keep the fish  250  confined within region  110 , the gap at the boundary of the side edges of divider plates  20  and  25  and the inner surfaces  75  of fish display tank  100  must be small enough to prevent fish  250  from passing between the divider plate edges and the fish tank walls. The boundary gap  105  between side edges  20   b  and  20   c  and display tank is depicted in FIG.  3 . The width of this gap may vary depending upon the size of fish  250 , and may be reduced to zero, in which case the side edges  20   b  and  20   c  would be flush with the tank inner surface  75 . Having the edges  20   b  and  20   c  flush with the display tank inner surface  75  is not preferred because this configuration restricts the flow of water between the regions  110  and  115 , and because the tight spacing makes it more difficult to insert and remove the separator assembly. For most species of fish, a gap of between 0.0625 and 0.25 inches would be sufficient to prevent the fish  250  from passing from the region  110  to the region  115 , but for larger fish this gap might be 0.625 inches or more. 
     When it is desired that the segregation of fish be completely mutual, such as when fish of different breeds or conflicting temperaments are confined to different aquatic regions, the width of the boundary gap should be such that the smallest of either type of fish would be unable to pass through. However, when completely mutual segregation is not particularly desired, the present invention may take advantage of the observed survival instinct of smaller fish to flee from larger fish. For instance, if fish  200  were smaller than fish  250 , and mutual segregation of the fish were not required, then fish  200  need not be confined exclusively to region  115 , and gap  105  need not be small enough to prevent their passage. So long as gap  105  is small enough to prevent larger fish  250  from entering region  115 , region  115  will provide an adequate sanctuary for the smaller fish  200 . 
     In FIG. 1, the central longitudinal axis of the cylindrical transit chamber is oriented substantially in parallel with the left-to-right axis of the fish display tank  100 , and orthogonally to the front-to-rear axis. Assuming that viewing is typically from the front of the display tank  100 , the left-to-right axis would typically be the long or “main” axis of the display tank (although either the left-to-right or front-to back axes could be considered “longitudinal” axes). Due to the width of the divider plates  20  and  25  in FIG. 1, and because the divider plates and the mouth openings to which they are attached are oriented symmetrically about the main longitudinal axis of the transit chamber, the side edges of divider plates  20  and  25  are adjacent to the inner side surfaces  75  of the fish display tank and meet those inner surfaces at angles that are nearly right angles. Thus, the divider plates  20  and  25  and the front and rear surfaces  75  are substantially perpendicular. This orientation of the divider plates is not required in all embodiments. The divider plates may form any angle with the inner side surfaces of the display tank, so long as the side edges of the divider plates are sufficiently close to the inner side surfaces of the display tank that fish larger than a selected size cannot pass through the boundary gap between the side edges and the display tank inner surfaces. In addition, the divider plates should remain substantially symmetrically disposed about the transit chamber so that the separator assembly  10  rests stably on the bottom of the display tank. 
     As stated previously, providing a boundary gap  105  promotes the flow of water between the region  110  and the region  115 . Thus, if the fish tank  100  is equipped with a water oxygenation/aeration unit, only one such unit need be provided, and it may be positioned to aerate the water within either region  110  or  115 . In FIG. 4 an alternative configuration of the divider plate  20  is depicted which further promotes the flow of water between regions  110  and  115 . Divider plate  20  and edges  20   a  and  20   b  are labeled as previously, and item  23  indicates the main central aperture through divider plate  20 . In this embodiment circular apertures  40  through divider plate  20  are added. These apertures are covered by mesh screen  45 , which is secured to plate  20  by small screws  60 . The mesh screen  45  must be sufficiently fine that at least the large fish cannot pass through it. Preferably mesh screen  45  and screws  60  are formed from non-corrosive materials such as nylon, other plastics, or a non-corrosive metal. Similar apertures with a mesh covering may be added to divider plate  25  in the manner depicted for plate  20 . 
     For proper stability, the components of the separator assembly (i.e., the divider plates  20  and  25  and the transit chamber  30 ) should be securely and rigidly affixed to one another. This can be achieved by having these components integrally connected to form a single piece unit. Alternatively, these components may consist of multiple attachable sections. One means of rigidly connecting multiple separator assembly sections is by use of a separable, attachable joint assembly, such as that depicted in FIGS. 5 a ,  5   b ,  5   c  and  5   d . In FIG. 5 a  one end of tubular transit chamber is fitted with a semicircular collar  50 , which is firmly connected to the lower periphery of the mouth opening by adhesives or by molding. A corresponding assembly is connected to divider plate  20  and consists of a spacer  55  and an outer housing  58 . Both spacer  55  and an outer housing  58  have a semicircular upper portion and a square lower portion (creating a substantially U-shaped appearance) with the semicircular portion of spacer  55  having a larger diameter than the semicircular portion of housing  58 . Spacer  55  and housing  58  are adjacent the lower periphery of aperture  23  of divider plate  20  and are connected to plate  20  by means of screws  300  and nuts  310 . Spacer  55  and outer housing  58  create a cradle for reception of collar  50 , allowing transit chamber  30  and divider plate  20  to fit together as depicted in FIG. 5 b . FIG. 5 c  shows the cradle assembly of FIG. 5 a  in an exploded view, including spacer  55  and outer housing  58 . FIG. 5 d  shows a cross section of FIG. 5 a  taken along the line B—B′. In this embodiment a similar type of connection would be used to join the other end transit chamber  30  to divider plate  25 . When transit chamber  30  and divider plates  20  and  25  are connected in accordance with the embodiment of FIGS. 5 a-d , a rigid connection is established that promotes stability of the separator assembly, but which also allows for easy disassembly for cleaning, or for packing and shipping. Preferably spacer  55  and outer housing  55  should be formed from rigid transparent materials, such as plastic or glass, and screws  300  and nuts  310  should be formed from non-corrosive metal or plastic. 
     FIG. 6 presents another embodiment of the present invention. In FIG. 6, fish display tank  100 , and divider plates  20  and  25  are labeled as previously, however, the divider plates  20  and  25  are now attached to alternative transit chamber  60 . Transit chamber  60  is generally spherical in shape and has openings  61  and  62  at opposing ends which are attached at their peripheries to divider plates  20  and  25  respectively, with the openings  61  and  62  being adjacent to the apertures through the divider plates. The generally spherical shape of transit chamber  60  allows more room for interaction between fish passing through the transit chamber. The divider plates and transit chamber may be attached by a non-water soluble adhesive, or may be molded from a single piece of material, or may be connected using the separable joint assembly depicted in FIGS. 5 a-d  or its equivalent. Also, the divider plates of this embodiment might also include the addition of mesh-covered apertures as described with respect to items  40  and  45  of FIG.  4 . 
     Because stability of the separator is enhanced when the transit chamber is completely submerged and filled with water, additional measures may be needed to insure complete submersion of spherical transit chamber  60 . These measures might include inserting a flexible hose or suction straw into air pockets that might have formed within transit chamber  60  when the separator assembly was placed within the water-filled display tank  100 , and using suction to eliminate the air pocket. This measure would ensure that transit chamber  60  is completely filled with water, providing both enhanced stability and a larger area for fish interaction. 
     FIG. 7 provides another variation of the embodiment of FIG.  6 . In FIG. 7 divider plates  20  and  25  are labeled as previously. In FIG. 7, a transit chamber is formed from generally spherical sections  74  and  76 , each of which have large circular openings cut through their surfaces, and sections  74  and  76  are joined at the perimeter of these openings along a generally circular connection zone  73 . The connection between sections  74  and  76  may be provided by forming corresponding male and female screw-type threads at the periphery of the cut-out portions of sections  74  and  76  and joining these threads in the zone  73 . Alternatively, the connection may be formed by use of a permanent or detachable joint in the zone  73 , or by adhering sections  74  and  76  together in the zone  73  with a non-water soluble adhesive, or by molding sections  74  and  76  from a single piece of material, etc. Sections  74  and  76  each have respective openings  71  and  72  that are attached respectively to divider plates  20  and  25 . The attachment of openings  71  and  72  to divider plates  20  and  25  may be by use of any of the previously described means of attaching the transit chamber to the divider plates. 
     FIG. 8 depicts a further embodiment of the present invention which combines features of the embodiments of FIGS. 1,  6 ,  7 , and  8 . Items identical to those in prior embodiments have the same numerical designations. In FIG. 8, plural transit chambers  35  and  83  are provided which are rigidly connected to divider plates  25  and  20 . Transit chamber  35  is similar to transit chamber  30  of FIG.  1 . Transit chamber  83  is similar to chamber  76  of FIG. 7, except that transit chamber  83  comprises three substantially spherical sections  85 ,  87  and  89 , which are rigidly connected to each other at the periphery of circular openings cut into their surfaces, and sections  87  and  89  are rigidly connected to divider plates  25  and  20  respectively. The attachment of spherical sections  85 ,  87  and  89  to each other may be accomplished by any of the attachment means described with respect to sections  74  and  76  of FIG. 7, including forming sections  85 ,  87 , and  89  into an integrally connected unit. In addition, the attachment of sections  85  and  89  to divider plates  20  and  25  may be by use of any of the previously described means of attaching a transit chamber to the separator divider plates. The divider plates  25  and  20  of FIG. 8 also include mesh-covered openings  40  previously described, which are optional. 
     A further embodiment of the present invention is depicted in FIG. 9 a . In FIG. 9 a , separator assembly  400  comprises hollow, substantially cross-shaped transit chamber  450 , consisting of orthogonally disposed and centrally connected cylindrical sections, and having four orthogonally disposed openings  450   a, b, c , and  d . Openings  450   a, b, c , and  d  are connected at their peripheries to divider plates  470   a, b, c , and  d  respectively. The divider plates  470   a, b, c , and  d  have apertures cut therethrough which are adjacent to and collinear with the openings the  450   a, b, c , and  d  of transit chamber  450  respectively. In the configuration of FIG. 9 a , symmetrically disposed divider plates  470   a, b, c , and  d  are positioned such that all sides, excluding the top and bottom, of transit chamber  450  are surrounded by the divider plate assembly. The width of divider plates  470   a, b, c , and  d  is such that adjacent side edges of neighboring divider plates are separated by a boundary gap  425 , which is sufficiently small that fish larger than a selected size cannot pass between the adjacent neighboring divider plates. Thus, divider plates  470   a, b, c , and  d  effectively divide fish display tank  100  into aquatic regions  410  and  415 , with the boundary of region  410  including the outer surfaces of divider plates  470   a, b, c , and  d , and the boundary of region  415  including the inner surfaces of divider plates  470   a, b, c , and  d . 
     In the embodiment of FIG. 9 a , the division of display tank  100  into aquatic regions  410  and  415  now depends solely on the separation between adjacent, neighboring divider plates, and not on the separation between the divider plates and the inner surfaces of the tank  100  itself Thus, there are fewer restrictions on the overall size and shape of the separator assembly  400 . So long as the outer dimensions of the separator assembly  400  are such that it will fit within the display tank, and so long as boundary gaps  425  are sufficiently small, divider plates  470   a, b, c , and  d  may take on any desired shape. Indeed, boundary gap  425  may be reduced to zero, in which case divider plates  470   a, b, c , and  d  may be formed into an integrally connected assembly. In such a case, for example, the divider plates might have a rounded cross-section and might even take on the shape of a cylindrical collar. As water flow between regions  410  and  415  is desired, some provision should preferably be made for allowing water passage, such as leaving appropriately sized boundary gaps  425 , or even providing a larger gap between adjacent divider plates while covering that gap by a mesh screen, such as mesh screen  480  shown in FIGS. 9 a  and  9   b . In FIG. 9 b , mesh screen  480  is stretched across the gap  425  and is adhesively attached to the sides of adjacent divider plates  470   a  and  470   b . If the apertures in the mesh screen  480  are small enough that fish larger than a selected size cannot pass through the mesh, boundary gap  425  need not be restricted in size and may be widened to promote water flow. Additionally, small water flow apertures maybe formed through the walls of the divider plate assembly or the walls of the transit chamber, so long as those apertures are sufficiently small that fish larger than a selected size cannot pass through them. 
     FIG. 10 depicts a further embodiment that combines certain features of FIGS. 6 and 9 a . The items depicted in FIG. 10 are labeled consistently with those of FIG. 9 a  except that transit chamber  450  is replaced by substantially spherical transit chamber  500 . The shape of transit chamber  500  may deviate from spherical to the extent necessary to provide adequate movement space for fish within the aquatic regions  410  and  415 . 
     It should be obvious to one of ordinary skill that numerous variations of size, shape, color, etc., of divider plates and transit chambers may be made without departing from the concept of the separator assembly of the present invention. In addition, various means may be employed for rigidly connecting the components of the separator, such as those described herein, and others. In addition, a separator assembly in accordance with the present invention may be constructed of many different materials; however, the materials used should be sturdy and corrosion resistant. Also, the materials used should be substantially transparent in order to maintain the appearance of an integrated, three-dimensional aquatic environment. 
     As a further improvement of the separator assembly described herein, sets of guide rails may be optionally added to facilitate quick and consistent insertion and removal of the separator assembly, such as for cleaning, without unnecessarily disturbing other fixtures or ornaments within the tank. FIG. 11 depicts an exploded view of a separator assembly  10 , as described with respect to FIG. 1, which is provided with a set of guide rails  600 , with one such guide rail provided for each side edge of divider plates  20  and  25 . Guide rails  600  have a generally rectangular cross-section with one open face extending longitudinally down one side of the rail, providing a generally U-shaped channel within the rail. 
     Each face of guide rail  600  that is opposite the open side of the rail is positioned parallel with and adjacent to an inner side surface  75  of fish display tank  100 . Preferably each such face of guide rail  600  is removeably attached to the adjacent inner side surface of the fish tank by a suitable attachment means, such as the suction cups  610  depicted in FIG.  11 . Alternatively, the guide rails may be permanently attached to the fish tank walls, such as with a non-water soluble adhesive, or by molding guide rails into the fish tank walls themselves. The U-shaped channels formed in each of the guide rails  600  comprise one or more slots, with the slot closest to the center of fish tank  100  (i.e., the innermost) being adapted for slideably inserting a side edge portion of either divider plate  20  or  25  therethrough lengthwise. In fact, the guide rails  600  depicted in FIG. 11 have two interior slots, an innermost slot,  603   a , which is adapted for slideable insertion of a divider plate side edge portion, and an outermost slot,  603   b , which is adapted for insertion of an isolator plate  620  or  625 . (The function of the isolator plates will be explained later herein.) 
     When fully inserted into the guide rails  600 , a portion of the divider plates should extend at least slightly above the surface water level of the fish tank  100 . The guide rails  600  may also have foot extensions  615  that are rigidly attached to the lower end of the guide rails. Preferably the foot extensions have suction cups  610  attached to their bottom surfaces in order to removeably anchor the guide rails  600  to the bottom surface of fish tank  100 . FIG. 12 depicts a separator assembly  10  provided with guide rails  600  as they would appear when placed within a fish tank  100 . FIG. 13 provides a top-down view of one of the guide rails  600  of FIG.  12 . As shown in FIG. 13, at least one suction cup  610  attaches guide rail  600  to inner surface  75  of the fish tank, while another suction cup  610  beneath foot extension  615  attaches guide rail  600  to the bottom of the tank. Because of the inherent stability stemming from the suction cup attachments of the guide rails, the stability of an associated separator assembly is promoted without relying solely on the symmetrical construction of the separator assembly. 
     In order to provide proper segregation of fish between the separated regions of a fish tank  100  provided with guide rails  600 , the boundary gap  650  between inner side surface  75  of the fish tank and the face of guide rail  600  that is parallel to surface  75  must be sufficiently small that fish larger than a selected size cannot pass through it. Similarly, if the guide rails  600  cause any gap to be created between the bottom edge of either divider plate  20  or  25  and the bottom surface of the fish tank, that gap must also reflect the dimensional constraint described for gap  650 . Of course, the bottom of guide rail  600  may be completely open allowing the bottom edges of divider plates  20  and  25  to rest directly on the bottom surface of the fish tank, in which case no appreciable gap would be created. 
     The isolator plates  620  and  625  allow removal of the separator assembly  10  from the guide rails  600  while providing continued segregation of the fish within the fish tank  100 . This facilitates cleaning of the separator assembly  10  by allowing it to be removed from the tank without having to remove any of the fish. Without isolator plates  620  and  625  in place, removal of the separator  10  would allow both groups of fish to have access to each other, with potentially disastrous consequences. 
     The isolator plates  620  and  625  should be substantially flat and planar and formed from a substantially rigid material, such as glass, plastic, or the like. To maintain the appearance of an integrated, three-dimensional aquatic environment within the fish tank, the materials used for the isolator plates  620  and  625  preferably should be substantially transparent. The thickness of the isolator plates should be such that the plates may be slidably inserted into the outer slots  603   b . The height of the isolator plates should be such that when the plates are fully inserted into the guide rails  600 , a portion of the isolator plates should extend at least slightly above the surface water level of the fish tank  100 . The submerged portion of the isolator plate should be completely impervious to the passage of fish larger than a certain size, so unlike divider plates  20  and  25 , there should be no passage aperture through the isolator plates  620  or  625 . For example, the submerged portion of the isolator plate  625  may comprise a solid piece of glass or plastic, or a material formed into a fine, but substantially rigid mesh. To facilitate insertion and removal, the isolator plates may be provided with an attached or integrally formed handle, such as top mounted, integrally formed handle  627  depicted in FIGS. 11 and 12. When the isolator plates  620  and  625  are in position in the outer slots  603   b  of the guide rails  600 , separator assembly  10  may be removed from the guide rails  600  while the fish within the tank  100  remain segregated. In particular, fish of a first group would be confined between an outer face of the isolator plates  620  and  625  and the inner surfaces  77  of the fish tank  100 , while fish of another group would be confined between the opposing inner surfaces of the plates  620  and  625 . If a rigid fine mesh is used for the isolator plates  620  and  625 , then fish smaller than a selected size may not necessarily be confined, but would be able to use one or the other of the isolated regions as a sanctuary. When it is once again desired to permit fish of one group to pass through the central area of the fish tank while remaining segregated from fish of the other group, then separator assembly  10  must be in place within the fish tank, and the isolator plates  620  and  625  must be removed (or at least positioned so as not to obstruct the passage apertures through the divider plates  20  and  25 ). 
     As with the components of the separator assembly  10 , it should be obvious to one of ordinary skill that numerous variations of size, shape, color, material, etc., of guide rails and isolator plates may be made without departing from the concept of the present invention. In addition, various means may be employed for removeably or permanently attaching the guide rails to the interior of the fish tank, such as by use of the suction cups described herein, and by other means.