It's sad but true -- not every fish is in perfect health. Here's how to pick the best of the bunch.

Difficulty: Average
Time Required:  20 minutes

Here's How:

1. Look at the top and sides of the tanks. If most are encrusted with residue, look for another shop entirely.
2. Look for clear water. If it's discolored, avoid that tank. If the water in most tanks is discolored, look for another shop.
3. Scan a half dozen tanks to see if any fish are sick or have died. If you see more than one sick or dead fish, find another shop.
4. Avoid tanks with decaying plants, as the water chemistry is questionable.
5. Do not buy fish that just arrived in the shop. They are stressed from travel, and might be carrying disease.
6. Avoid fish with cloudy eyes, torn or clamped fins, and spots or sores on their body.
7. Avoid fish that are sluggish or appear to be shivering.
8. Look at all the fish in the tank. If any appear sick, don't buy a fish from that tank.
9. Choose an active, alert fish. Take him home and enjoy your new pet.

Tips:

1. Ask the shop about their fish guarantee. Good shops will replace fish that die within the first day or two.
2. Quarantine new fish in a separate tank for three days before moving them to the regular tank.

More How To's from your Guide To Freshwater Aquariums