<PAGE>   1
                                                                   EXHIBIT 10.33


                     FIFTH AMENDMENT TO CREDIT AGREEMENT

         This Fifth Amendment to Credit Agreement, dated as of December 31,
1995 (this "Agreement") is between Atlantis Plastics, Inc., a Florida
corporation ("Borrower") and Heller Financial, Inc., a Delaware corporation for
itself as Agent and as Lender ("Heller").

                                  RECITALS

         A.      Borrower and Heller are parties to that certain Credit
Agreement dated as of February 22, 1993, as amended from time to time (the
"Credit Agreement").  Capitalized terms used but not defined herein shall have
the meanings ascribed to such terms in the Credit Agreement.

         B.      Heller and Borrower desire to amend the Credit Agreement, as
provided herein.

         NOW THEREFORE, in consideration of the foregoing, the covenants and
conditions contained herein, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

         1.      Amendment to the Credit Agreement.

                 A.       Subsection 1.1 of the Credit Agreement is hereby
amended by adding the following definition in its proper alphabetical
order:

                 "Adjusted Total Debt" means the sum of the Indebtedness minus
         the outstanding balance of the Revolving Loan on the last day of the
         Fiscal Month plus the average daily balance of the Revolving Loan for 
         the Fiscal Month.

                 B.       Subsection 1.1 of the Credit Agreement is hereby
amended by deleting paragraph "(a)" of the definition of "Eligible Accounts" 
in its entirety.

                 C.       Subsection 1.1 of the Credit Agreement is hereby
amended by deleting paragraphs "(b)" and "(c)" of the definition of "Eligible
Accounts" in its entirety and replacing paragraphs "(b)" and "(c)" with the
following:

                          "(b)    Accounts which remain unpaid for more than 
          ninety (90) days after the invoice date;"

                          "(c)    Accounts due from a customer whose principal
         place of business is located outside the United States of America
         (other than Accounts due from one or more customers whose principal
         place of business is located in Canada provided such Accounts are
         Collateral pursuant to perfected
<PAGE>   2

         Canadian security interest) unless such Account is backed by a letter
         of credit issued or confirmed by a bank that is organized under the
         law of the United States of America or a State thereof and has capital
         and surplus in excess of $250,000,000; provided that such letter of
         credit has been duly assigned and delivered to Agent as additional
         collateral under the Security Documents;

                 D.       Subsection 2.1(A) of the Credit Agreement is amended
by deleting the second sentence thereof and substituting the following in its
place:

         "The aggregate amount of all Revolving Loan Commitments shall be
determined by the ratio of Adjusted Total Debt to EBIDAT (where EBIDAT is
calculated on a trailing twelve (12) Fiscal Month basis), as determined on the
most recently ended Fiscal Month (for which the monthly financials have been
delivered pursuant to subsection 5.1(A)) in accordance with the following
table:

<TABLE>
<CAPTION>
Adjusted Total Debt to EBIDAT              Maximum Revolving Loan Commitment
-----------------------------              ---------------------------------
<S>                                                 <C>                
Greater than or equal to 5.75                       $17,500,000        
Greater than or equal to 5.50                       $20,000,000        
Greater than or equal to 5.25                       $22,500,000        
Greater than or equal to 5.00                       $25,000,000        
Greater than or equal to 4.75                       $27,500,000        
Less than 4.75                                      $30,000,000        
</TABLE>

         or as reduced from time to time pursuant to SUBSECTION 2.4.  The
aggregate amount of the Maximum Revolving Loan Commitment as determined above
shall be effective as of the first Business Day of the next Fiscal Month
following the receipt of the monthly financials of the most recently ended
Fiscal Month."

                 E.       Subsection 6.2 of the Credit Agreement is hereby
deleted in its entirety and replaced with the following:

                 "6.2     Fixed Charge Coverage.  The Fixed Charge Coverage, on
         a trailing twelve (12) Fiscal month basis, shall not be less than:
         (i) .70 for the Fiscal Quarters ending March 31, 1996, June 30, 1996
         and September 30, 1996; (ii) 0.9 for the Fiscal Quarters ending
         December 31, 1996; and (iii) 1.0 for the Fiscal Quarter ending March
         31, 1997 and thereafter.

                 F.       Subsection 6.3 of the Credit Agreement is hereby
deleted in its entirety.

                                       2
<PAGE>   3


                 G.       Subsection 6.4 of the Credit Agreement is hereby
deleted in its entirety and replaced with the following:

                 "6.4     Adjusted Total Debt to EBIDAT.  Adjusted Total Debt
         to EBIDAT, on a trailing twelve (12) Fiscal Month basis, shall not be
         greater than 6.25 at the end of the Fiscal Quarter ending June 30,
         1996 and each Fiscal Quarter thereafter."

                 H.       Subsection 6.5 of the Credit Agreement is hereby
amended for the applicable periods as follows:

<TABLE>
<CAPTION>
               Period                                                 Amount
               ------                                                 ------
         <S>                                                        <C>
         December 31, 1995                                          $18,500,000
         March 31, 1996                                             $16,000,000
         June 30, 1996                                              $19,000,000
</TABLE>

         2.      Formation of Atlantis Foreign Sales Corporation.

         Borrower has advised Heller that Borrower has formed a new Subsidiary
known as Atlantis Foreign Sales Corporation ("AFSC"), which is chartered in
Barbados and which will serve as a foreign sales corporation in accordance with
the rules and regulations promulgated by the Internal Revenue Service.  The
Credit Agreement permits the formation of such Subsidiary without Heller's
prior written consent provided that the new Subsidiary becomes a Subsidiary
Guarantor.  It is Borrower's and Heller's understanding that Heller's consent
to formation of AFSC is not required provided that: (i) AFSC executes a
Subsidiary Guaranty, (ii) AFSC executes a Subsidiary Security Agreement, (iii)
Borrower shall pledge 100% of the capital stock of AFSC to Heller as additional
Collateral to secure the Obligations and, in connection therewith, the Borrower
shall execute and deliver an appropriate amendment to the Borrower Pledge
Agreement; (iv) Borrower shall execute a bank agency agreement covering funds
received by AFSC; and (v) funds received by AFSC shall be transferred to
Borrower no later than the end of the next business day following receipt
thereof.

         3.      Formation of Netherlands Subsidiary.

         Borrower has advised Heller that Borrower intends to form a new
Subsidiary which will be chartered in The Netherlands to act as a distributor
of Borrower's products ("Netherlands Sub").  It is Borrower's and Heller's
understanding that Heller's consent to the formation of Netherlands Sub is not
required provided that:  (i) Netherlands Sub executes a Subsidiary Guaranty,
(ii) Netherlands Sub executes



                                       3
<PAGE>   4

a Subsidiary Security Agreement, (iii)  Borrower shall pledge 100% of the
capital stock of Netherlands Sub to Heller as additional Collateral to secure
the Obligations and, in connection therewith, the Borrower shall execute and
deliver an appropriate amendment to the Borrower Pledge Agreement.

         4.      Conditions of Effectiveness of this Agreement.

                 The effectiveness of this Agreement is expressly subject to
the following:

                 (a)      No Default or Event of Default under the Credit
Agreement, as amended hereby, has occurred and is continuing; and

                 (b)      Execution and delivery of the security documents
pursuant to paragraphs two and three hereinabove; and

                 (c)      No default shall exist and be continuing under that
certain Indenture by and between Atlantis Group, Inc. and American Stock
Transfer & Trust Company, as trustee dated as of February 22, 1993.

         5.      Representations and Warranties.  To induce Heller to enter
into this Agreement, Borrower represents and warrants to Heller that:

                 (a)      Authority and Binding Effect.  The execution,
delivery, and performance by Borrower of this Agreement is within its corporate
power, has been duly authorized by all necessary corporate action (including,
without limitation, shareholder approval), has received all necessary
government approvals (if any shall be required), and does not and will not
contravene or conflict with any provision of law applicable to Borrower, the
Certificate of Incorporation or Bylaws of Borrower, or any order, judgment, or
decree of any court or other agency of government or any agreement, instrument,
or document binding upon Borrower; and the Credit Agreement as heretofore
amended and as amended as of the date hereof is the legal, valid, and binding
obligation of Borrower enforceable against Borrower in accordance with its
terms.

                 (b)      No Default.  No Default or Event of Default under the
Credit Agreement, as amended hereby, has occurred and is continuing.

                 (c)      Warranties and Representations.  The warranties and
representations of Borrower contained in this Agreement, the Credit Agreement,
as amended hereby, and the Financing Agreements, shall be true and correct as
of the date hereof, except as disclosed on Schedule 5(c) attached with the same
effect as though made on such date except to the extent



                                       4
<PAGE>   5

that such representations and warranties expressly relate solely to an earlier
date, in which case such representations or warranties were true and correct as
of such earlier date.

         6.      Miscellaneous.

                 (a)      Captions.  Section captions used in this Agreement
are for convenience only, and shall not affect the construction of this
Agreement.

                 (b)      Governing Law.  This Agreement shall be a contract
made under and governed by the laws of the State of Illinois, without regard to
conflict of laws principles.  Whenever possible, each provision of this
Agreement shall be interpreted in such a manner as to be effective and valid
under applicable law, but if any provision of this Agreement shall be
prohibited by or invalid under such law, such provision shall be ineffective to
the extent of such prohibition or invalidity, without invalidating the
remainder of such provision or the remaining provisions of this Agreement.

                 (c)      Counterparts.  This Agreement may be executed in
counterparts, each of which counterparts shall be deemed to be an original, but
all of such counterparts shall together constitute but one and the same
Agreement.

                 (d)      Successors and Assigns.  This Agreement shall be
binding upon Borrower and Heller and their respective successors and assigns,
and shall inure to the sole benefit of Borrower and Heller and the successors
and assigns of Borrower and Heller.

                 (e)      References.  Any reference to the Credit Agreement or
the Financing Agreements contained in any notice, request, certificate, or
other document executed concurrently with or after the execution and delivery
of this Agreement shall be deemed to include this Agreement unless the context
shall otherwise require.

                 (f)      Continued Effectiveness.  Notwithstanding anything
contained herein, the terms of this Agreement are not intended to and do not
serve to effect a novation as to the Credit Agreement.  The parties hereto
expressly do not intend to extinguish the Credit Agreement.  Instead, it is the
express intention of the parties hereto to reaffirm the indebtedness created
under the Credit Agreement which is evidenced by the notes provided for therein
and secured by the Collateral. The Credit Agreement as amended hereby and each
of the Loan Documents remain in full force and effect.




                                      5
<PAGE>   6

         Delivered at Chicago, Illinois, as of the date and year first above
written.


                                   ATLANTIS PLASTICS, INC.
                                            (f/k/a Atlantis Group, Inc.)
                                   
                                   By: /s/ Peter Kacer
                                       ------------------------------
                                   Name Printed: Peter Kacer
                                        -----------------------------
                                   Title: Vice President & Controller
                                          ---------------------------
                                   
                                   HELLER FINANCIAL, INC., for itself
                                   and as Agent for the Lenders
                                   
                                   By: /s/ Andrew D. Marek
                                       ------------------------------
                                   Name Printed: Andrew D. Marek
                                                 --------------------
                                   Title: Vice President
                                          ---------------------------




                                       6