A good fish shop is clean and well maintained. Look around, if you see any of these conditions, it should make you think twice about the shop.
- Items stocked on the shelves are dusty.
- Items, particularly food, is outdated.
- Floors are dirty, have wet spots or stains.
- Tank stands and tank exteriors are dirty.
The condition of the tanks is particularly crucial. If they are not well maintained, the health of the livestock is questionable. Here are some things to look for.
- Are the tanks free of algae?
- Is the water clear and free of floating debris?
- Is the water level filled close to the top?
- Are the tanks well covered and lit?
- Are work areas clean and tidy?
The health of the fish is a key factor to consider. Although some health conditions are not easy to discern, there are some signs to look for.
- Are the fish perky and active?
- Do fish have frayed fins, open sores, fungus, or missing eyes?
- Are there dead fish in several tanks?
- Are there skeletal remains of fish in the tank?
I consider store personnel are one of the most important factors when choosing a fish shop. The skill of the staff is what sets apart a department store that sells fish, and a professional fish shop. If the staff don’t know much about the care of fish, it’s unlikely the fish are being properly cared for.
Does the staff ask you questions before selling you fish? Top notch stores will make sure you aren't making a blunder like overstocking your tank, or putting the wrong fish together (the two most common mistakes for beginners). Ask about the proper food and tank conditions for the fish you are going to purchase. The staff should know those things, or they will immediately find a coworker who does.
Good stores will have at least a 48 hour replacement policy for live purchases. They should ask you to return the deceased fish as well as a water sample for testing. If they don't you should be wondering why they replace fish carte blanche. Is it because they often sell diseased or stressed fish, and expect to replace them?
Specialty vs General Pet store
Although not all mega pet stores are bad, those that carry everything under the sun (ie: dogs, cats, birds, ferrets, reptiles, etc) often don't have the depth of expertise in aquariums that a specialty store does. I've also found that locally owned stores are more likely to be concerned about ensuring that you are successful.