## 3 Results  
### Behaviors and Clinical Signs  
The experimental infection process was separated from the 5-hour feed period for all groups. Fish infected with _A. salmonicida_, _A. veronii_, _A. bestiarum_, _A. ltydrophilia_, _A. caviae_ and _A. sobria_ showed at least one change in the evaluated behaviors or clinical sign. The presentation of darkening of the skin in fish infected with _A. salmonicida_ (18.8%), _A. veronii_ (15.5%) and, _A. ltydrophilia_ (11.1%) was observed with statistical differences; meanwhile fingerlings infected with _A. allosaccharophilia_, _A. bestiarum_, _A. caviae_, _A. lusitana_, _A. media_, _A. popoffii_, _A. sobria_, and the control group, did not present color changes (\(p>0.05\)) (Table 1) (Figure 1a).  
\begin{table}
\begin{tabular}{c c c} \hline
**Behavior or Clinical Sign** & **Definition** & **References(s)** \\ \hline Loss of appetite & Fish refuse to eat and/or lose interest in food (anorexia) & [12; 17; 19; 20; 21] \\ Abnormal swimming (Erratic swimming) & Loss of consistency, regularity and/or uniformity in & [17; 22] \\  & movement; fish swimming in different directions & \\ Hyperpigmentation and/or darkened skin & Fingerlings show an excess of melanin pigmentation in & \\  & the skin, giving them a darker color & [1; 9; 12; 23] \\ \hline \end{tabular}
\end{table}
Table 1: _Aeromonas_ species and histopathological lesions observed in nasal epithelium or rosette, telencephalon, and oblongata medulla changes (%), observed in rainbow trout fingerlings infected with _Aeromonas_ spp.  
Figure 1: Rainbow trout fingerlings experimental infected by immersion with different _Aeromonas_ species. (**a**) Fingerlings control group. Bar = 1 cm.; (**b**) Fingerlings present different darkening skin grades (asterisk), infected with _A. salmonicida_. Bar = 1 cm.; (**c**) nasal epithelium, moderate edematous and severe hemorrhagic rhinitis (plus sign) on fingerlings infected with _A. lusitana_; (**d**) nasal epithelium, suppurative rhinitis in fingerlings infected with _A. salmonicida_, neutrophil (greater-than sing) and macrophage (hyphen-minus) infiltration were observed; (**e**) nasal epithelium with bacterial shapes on the surface (circle), in fingerlings infected with _A. salmonicida_; and, (**f**) oblongata medulla, slight focal myelitis (asterisk) in fingerlings infected with _A. lydrophila_.  
The lack of appetite or inappetence in fingerlings infected with _A. salmonica_ (47.7%), _A. hydrophila_ and _A. sobria_ (46.6%), _A. caviae_ (38.8%) and, _A. besiarum_ (32.2%), was observed with a statistical difference (_p_ > 0.05) for _A. allosacacharophilis_, _A. lusitana_, _A. media_, _A. popoffii_, _A. veronii_, and the control group, who showed no changes in their feeding behavior or feeding regulation. Finally, fingerlings infected with _A. besiarum_ (83.3%), _A. hydrophila_ (74.4%), _A. sobria_ (67.7%), _A. salmonica_ (66.6%) and, _A. caviae_ showed erratic behavior changes, a loss of consistency and a loss of swimming uniformity. No significant statistical differences (_p_ > 0.05) were noted for the _A. allosacacharophilis_, _A. lusitana_, _A. media_, _A. popoffii_ and _A. veronii_ groups or the control group (Table 2).