While it’s tempting to use the same method when choosing pet fish, it’s not realistic. Instead, there are vital characteristics to consider when you are looking through the glass of the pet fish aquarium in the store or shop:
SCHOOLABILITY–YOURS AND THEIRS
Before choosing any pet fish, read up on breeds and needs: will you be able to maintain their health (their specific diets) and their environment (the chemical balances in and temperatures of the water)? For example, will you need algae-control and, therefore, will look into getting a clownfish or catfish? (If catfish–which some warn against for their predatory dispositions, then pay heed to the next section.)
Also, before selecting pet fish, consider getting fish that school together. In other words, if you get more than one breed or species, is compatibility important (or do you prefer fish that fight, bite at and eat each other)?
SIZE AND NUMBER
When buying your chosen pet fish, consider the number of them you want, and ask yourself, can your tank accommodate 2 inches of fish for every gallon of water in the tank? Remember that some fish (like catfish) grow–quite big and quite long–so consider if you can replace the container in a couple of years for them to swim unencumbered and for your pet fish still to have plenty of hiding space(s), as well.
When you visit the shop, how well cared for do the pet fish tanks appear? Are the sides and tops free of gook and grunge? If not, avoid shopping at that store. Are the plants in the containers healthy? Is the tank water (in all tanks) clean and clear? If not, the water chemistry is imbalanced and/or has not been cleaned, and therefore the fish will be suspect.
Are the pet fish you are considering new arrivals? If so, they may have a disease or be too stressed from travelling for more re-locating stress. As you look at all tanks, if any fish in any container is dead or any fish has cloudy eyes, a torn fin, or body sores, or any fish that is shivering or sluggish, go to another shop for active, alert, plump, and colourful fish. Though not candy–not a penny apiece and not edible…ahem–you want to be as delighted in the pet fish store–hands and breath on glass–as you were in the kids’ candy store. Only more so.