Tips for choosing a healthy discus, arowana or angelfish are no different from choosing any other fish. Fins should be erect, not frayed and without kinks, the belly should be full, head should be in the right proportion to the body, colours must be bright (not dull), eyes should be clear, no unusual spots or blemishes should be present.
However, before embarking on choosing the right fish, you must first be sure to choose the right shop. Choosing a good shop and choosing a good fish go hand in hand. Why is this so?
A good shop will take pride in their animals and will spend the required money to provide a healthy environment for their fish and hence ensure you have fish in excellent condition.
A good shop will have knowledgeable helpful workers who are always willing to share this with you. Check for good fish health practices. Are different nets used and are they being disinfected between tanks? Do the workers provide advice on introducing the fish to your tank and do they recommend quarantine? Do they provide a water quality testing service?
Check what other fish are kept in the tank. Make sure that they are just as healthy. Check the filtration system and see if these are shared with any other tanks. Some fish diseases can be transmitted between species. Hence, make sure you check the health of the fish in those other tanks.
Watch their behaviour. Some fish do twitch a little as a form of communication. Watch that fish are not flashing, or doing anything else unusual. The only type of fish that should be swimming upside down is the 'upside down catfish'. Do some research on the fish of your choice and know the normal range of behaviours for your fish.
And finally, it is important to check out all the other fish tanks in the shop. It will provide an insight as to how these fish have been treated. Check all the tanks in the shop. Ensure all fish are healthy. Look for signs of excessive use of medication (i.e. green, yellow or blue water). A good shop will not try to sell fish that are undergoing treatment and that there are no decomposing, dead or dying fish lying around in tanks.
A good shop will provide you with healthy fish. But keeping a good shop with healthy fish may incur extra expenses to the management. This means that when buying a healthy fish, the expense may be higher. This investment on your part will prove beneficial, not just for your fish and your aquarium, but for improving fish health and welfare across the entire industry.
Enjoy your fish!