How to Buy Healthy Fish

So you are at your local aquatics center and you have seen some fish you want to add to your collection; you’ve checked their compatibility with your other fish and water (see previous post on chemistry) but what else should you be looking for to make sure you are buying healthy fish?

While there is no way to know for sure that the fish you are buying are healthy, there are a few tell tale signs that they might not be. The list below is not exhaustive, but is generally what I look for when deciding whether to buy fish or not and applies fairly universally from tropical aquarium fish to pond fish:

  • Does the fish have all its fins, and are they in good condition?
  • Is the fish swimming normally or is it struggling to stay the right way up? (Note: certain catfish of the synodontis family spend a lot of time upside down hence the common name “upside down catfish”)
  • Is the fish resting on the bottom a lot? (Again some fish spend a lot of time on the bottom – catfish for example, however if something like a tetra or a goldfish is sitting on the bottom I’d be concerned)
  • Does the fish look “normal”? Are the gills inflamed or protruding? Are its scales sitting flat against its body? Does it have a swollen belly/looking malnourished? Does it look like the other fish of that type you have seen/others of the same species in the tank?
  • Do the other fish look healthy? Perhaps one dead fish in a tank of tetras isn’t enough to call the whole thing off, It’s inevitable that fish die however if there are multiple dead or dying fish in the tank with the fish you want to buy, it probably isn’t worth the risk.
  • Do fish in other tanks appear to be ill or dying? A lot of aquatics places will have water entering each tank from a larger sump, probably not all the tanks from the same one but probably in groups. If a significant number of fish in the tanks surrounding the one of interest are showing signs of illness, if that illness if contagious there is a good chance it’s already in all the tanks even if symptoms are yet to show.
  • Do ANY of the fish show obvious signs of disease? In particular here I’m talking about white spot disease which, as the name suggests, will appear as white spots about the size of a pin head on the fish. It starts off as one or two spots, but if left will cover the entire fish and eventually kill it. White spot is highly contagious and can wipe out the entire population of a tank if left untreated – a dedicated blog post on white spot will follow.

Other, more subtle things I usually consider are based more on intuition and experience and are the sort of things you pick up as you get more accustomed to buying fish from a variety of places and include:

  • Do the aquaria appear to be well maintained? Although dirty glass isn’t inherently dangerous in and of itself, cleaning the glass is usually done before a water change – if they aren’t cleaning the tanks are they maintaining the water quality?
  • Have you bought from there before? If the answer is no then obviously this is a moot point, however if you have bought apparently healthy fish that didn’t survive long then the problem is either with you or with them, and if you’re confident in everything your end then perhaps they are a shop to avoid. Alternatively if you are less confident in your procedure then perhaps look for improvements and try again.

Another piece of advice I would give is to do some basic research, even if it’s on your phone whilst in the shop. I often go to a shop knowing what I am after and have researched it before so I know what to expect. You will occasionally find that some retailers sell such a variety of different fish that they are not completely up to speed on the requirements of each species. Sometimes a particular species may have specific requirements that if not met will not cause a problem in the short term but over longer time frames can cause problems – basically, just because that’s how the shop kept them, doesn’t mean you should too.

A prime example of this is puffer fish. There are a number of species of puffer fish where there is some debate over whether they are truly marine, brackish or freshwater species. Many will be sold as freshwater species however with a bit of research you learn they really prefer brackish water. These fish will almost certainly not attain their true lifespan or enjoy a good quality of life if you keep them in non-optimal conditions, even if they appear fine in the short term. Another point worth considering is if you do chose to buy a brackish water fish that has been kept in fresh water and you intend to move it into a brackish set-up, I would recommend slowly increasing the salt content to the desired level to avoid causing the fish undue stress and damage due to a sudden change in water chemistry.

Another example is the red claw crab – often seen in a normal aquarium set-up it will survive long enough for you to believe that everything is alright, however in the medium to long term they must have access to land areas (or at least drift wood above the water surface) and some people suggest the addition of salt too.

One final piece of advice would be this: do not be tempted to buy fish you think are ill or dying in an attempt to save them. Invariably if they have got to the state where you can tell they are not right, there is probably not a lot you can do and you risk the wellbeing of all the other fish in your tank.

FYI – I buy nearly all of my fish from the various Maidenhead Aquatics branches near me (the photo is from one of their stores). Over the years I have found most of their staff to be very friendly and knowledgable, and would recommend them as a great place to buy your fish!



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