It would be better while choosing your desired fishes for your aquarium you can select the best ones. The following behavior / signs may be an indicator of best ones.
- Normal swimming behavior ( Relax manner, not jerkily or with nervous movement)
- Belly /abdomen out line are also another indicator of selecting best fish. Good specimens have rounded belly outline; whereas poor specimens have shrunken-in-stomachs. This is observed in livebearers like Swordtails, Guppies, Mollies and Platies and also in Gold fishes.
- Do not bye fish where fishes showing shaky behavior and remain standstill.
- No sign of any (white) spots over the body surface.
- Fins should be erected and there should not be any cut in any fins. Bloody fins should be avoided because they are sign of stress.
- There should not be any external parasites attached to the body may in oval (Argulus) or filament (Lernea) shaped.
No external injury or nay wooly structure (fungus) seen in fish body.
