What To Look For When Purchasing A New Fish

The purchase of a new fish be this your very first one or a new one to an existing aquarium already stocked with fish can be a very exciting time. Due to the excitement this can often result in impulse purchases.

Everyone is tempted to purchase on impulse and it is one of the hardest things to come to terms with. You go into the fish shop and in the display aquariums are some exceptionally beautiful fish swimming around all saying ‘buy me, buy me!’

This is a temptation however which needs to be resisted at all times. If you are presented with this opportunity try to take a step back and if it is a fish that you would like then ask the store to hold it for you whilst you check your aquarium and research it’s requirements. You can always go back and purchase it later.

It is very important in my opinion to have an idea as to what you are going to stock in the aquarium. All the fish in the aquarium need to get on with each other. Quite probably a lot of the fish in the aquarium will be from different areas of the world and in nature they would never see each other. The last thing you want to happen in the aquarium is for ant type of fighting or territorial behaviour to start. You want an aquarium where all the fish live in harmony with each other.

Prior to going to the fish store to purchase a fish it is imperative that you check all the water parameters to ensure that they are ok.

Once at the fish store however how are you going to tell a good fish from a bad one.

Actually thinking about it the word bad is probably not the correct one to use here – a better way to say it would be a fish which is in better condition than another fish.


Colour is actually quite a hard one to use to base your decision on but it is a good starting point.Looking at is the colour of the fish in relation to other fish which are the same may show that the fish has been collected correctly, handled properly, acclimatised to the aquarium correctly and is settled in the stores display aquarium.

It does need to be noted however that the colour of the same species of fish can vary in their natural appearance so although colour is a good general indication of the overall health of the animal there are others which need to be taken into consideration.


How is the fish moving?

Of course all fish have different swimming patterns and this does need to be taken into consideration. What we are looking for in this area is that the fish is able to hold position in the aquarium with minimal effort and does not appear to be irritated or alarmed in any way. This is dependant upon the fish but swimming with the head facing down for example may be an indication of an issue with the swimbladder.

As said all fish have different swimming patterns and it will take time for you to understand what is good, what is bad and what is natural.

The Eyes

When looking to the eyes of a fish they should be both clear and bright. There should not be any cloudiness to the eyes or any type of growth, There are quite a few eye problems which can be encountered in fish. The majority of these can be treated however I personally would not purchase on which requires treatment unless it was treated in the store first and I could inspect it further before deciding to make a purchase.

Another area to look for is where the eyes appear to protruding from the fish’s head.

The Fins

The fins on the fish should be clear and show no form of speckling or cloudiness. There are various infections, normally parasitic which become obvious when inspecting the fins of the fish.

The fins should not be damaged in any way. This is not normally due to infection but is due to fighting, netting or scratching. Whilst damaged fins do heal quickly there are prone to infection and if the fish is placed under the stress of being captured then this risk increases.

The Body

Inspecting the body of a fish tells us a lot about the overall health of a fish. Obviously fish of different species have different shapes and it may be surprising to hear that fish from the same species can also have different shapes. For example captive bred fish. Captive bred fish sometimes are shaped differently to that of their counterparts in the wild.

The main reason the fish’s body is inspected is so we can see if it has been feeding correctly. Fish who have not been feeding correctly are normally quite thing when you look down their sides from the front. Their body appears to look pinched which in turn makes their head look larger than their body.

It can also sometimes mean that there is underlying problem with infection or stress. Whilst thin fish can be fattened up this does take time, care and patience and I would not recommend that the beginner take this task on until more experience is gained.


On some occasions fish display small symptoms in relation to problems, infections etc. Their bodies may look ok, their fins intact, the eyes clear and the fish is moving correctly however the fish could be breathing heavily. This can be seen by watching the gills of the fish. If they are beating fast then there may be an underlying problem. This does not mean that there is a problem but it should raise concern as you simply do not know if the fish is poorly or not.


One of the most useful things to do and unfortunately one of the least done things is watching the fish feed. Even fish that may be poorly may feed well but if a fish shows no desire to feed then realistically it should not be purchased. Fish when feeding are opportunistic and rarely turn a meal down.

There are some fish which are hard to feed or have a strict diet. It is of my opinion that these types of fish are not suitable for the beginner and should be investigated when more experience is gained.

There are also some fish which are healthy in all areas but simply refuse to feed. In the end unfortunately these fish are going to die and although you may try everything you can to get them to feed ultimately this will often end in dissapointment. There is also another concern with this is that when you are trying to get a fish to feed you will probably introduce more food than you would normally and then your water quality will suffer ultimately putting your other corals, fish etc at risk.

Therefore it is essential that you ask the dealer to feed the fish in front of you. Don’t stand to close to the aquarium when this is performed. Stand back and watch the fish feeding. You will know very quickly if it is going to feed or not. The fish should be enthusiastic about the food offered and dash around the aquarium looking for food to consume.


So there we go – an article which details what to look out for when purchasing fish. This is an area, among many which a lot of aquarists do not do and a lot of fish die plus a lot of aquarists are upset, dis-heartened etc because of it. It does not take long to do and the ultimate long health of the fish will be better plus your enjoyment looking after it.

Also remember that when the fish is purchased it should be captured correctly by the store owner, bagged correctly and then once taken home it should be both acclimatised and quarantined correctly.

On another matter a lot of people are now purchasing fish online as well as other animals for the aquarium. This article does not cover this however a while ago we created a short guide detailing what to do when purchasing fish online. This is a PDF document and can be downloaded from the link below:


  1. If you’re at the store long enough, also examine the fish’s waste. It should not be white, as this is usually a sign of internal parasites.

  2. Some really valid points any of which can make your fish buying experience much better.

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