I would like to buy fish that have been treated properly before being sold.

The first thing that jumps out at me is that obviously a bigger tank is better. One online resource I found essentially recommended a 10 gallon minimum for any fish. The pet store obviously does not follow this rule.

More generally, this seems like an uphill battle since I live in New York, where space of any kind is at such a premium that it's hard to imagine more space than is physically necessary being invested in selling a fish.

I don't think overcrowded fish for sale speaks well to their health or background or the care or concern of whatever breeder or corporation or farm happened to produce them.

How can I tell if a particular seller treats his fish well?


The thing is, yes pet stores have over crowded aquariums, but consider that the fish's lifespan in the aquarium is short as they are continuously being sold.

Another thing is, selling these fish is the pet store's job, so they takes care of them everyday and provide the best filtration systems to keep there job running, unlike us at homes where we do that every week. Unless the pet shop is small and doesn't do that. I have seen some local pet stores having over crowded aquariums with really poor conditions, i would never buy my fish from there.

One last thing, i always put my new fish in a 10gal hospital aquarium for some time before i move them into my 55gal to make sure they are fine and don't have any disease or anything else.


You are right that tanks at most pet/aquatic retailers are crowded and would be considered massively overstocked.

The main risks of overcrowding are:

  • Increased bioload - more difficult to maintain water quality and keep parameters at an acceptable level

  • Growth problems - overcrowding may stunt growth - this can eventually kill fish as their internal organs continue to grow

  • Aggression - if fish do not have enough space they may become aggressive

How pet stores get around these issues:

  • Powerful filtration systems to keep up with the high bioload

  • Quick turnaround time - fish are only kept in these conditions for a short period

  • Chemicals in the water to prevent stress and disease

Whenever you buy a fish, regardless of where you get it from, it is recommended to quarantine the fish for 2+ weeks to ensure it shows no signs of disease. This helps to minimise the risk to your current tankmates.

I would also avoid adding the water fish come in to an established aquarium due to the unknown contents.


They most certainly are a thing, but typically a general pet store (or any large corporation IMO) will treat the fish just as another product on the shelf.

A reputable store will

  1. Know a lot about the specific fish and the hobby in general.
  2. Know where the fish come from (ie wild caught or captive bred).
  3. The tanks will appear in good shape and the fish will appear active/healthy. New arrivals will be stressed out from shipment, but any fish that has been in for a few days should be adjusting. Also, some fish just get sick. This should be addressed and not silently dying in the corner.
    • However, if I see saltwater tanks with cyano, excessive algae, gasping or sickly fish, etc; I won't buy even the healthiest looking one of the lot. They should also be willing to feed it in front of you to prove this.
  4. The store will try not to just sell you a fish that you can't handle or isn't compatible with your setup. Everyone I deal with actually cares if the fish lives when you take it home.

This is by no means an exhaustive list. To address your overcrowding concern: Yes everyone said about large filters but something missing was most fish stores have a large communal body of water shared amongst the tanks. Think about having a large tank as apposed to several smaller ones (adding up to the same volume) and piping them together. There are of course other factors to consider in what constitutes a proper setup, but that would turn this answer into a book.

The bigger difference in the latter case is ensuring the fish have enough room to be happy/healthy. But then again, this is hopefully a short term home for the fish.

  • 1
    another one: a good store will have muted lighting outside the acquarium area. This provides both better visibility of the fish inside the tanks, and make the fish less skittish from all the people roaming outside. They'll also have proper lighting, different spectrum tubes depending on the specific fish in a tank (though that may well be very hard to see for most people).
    – jwenting
    Nov 11 '14 at 7:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.