Choosing Your First Fish For Your Tank

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Popular fish such as guppies and neons, despite often being recommended, are actually some of the worst choices for your first fish. To choose the correct fish it is important to understand what the difference is between fish that will do well in a new tank and those that may suffer.

Customer receiving bag of fish

Qualities to look for

The first fish must be able to withstand the water quality fluctuations common in new aquaria and to resist diseases caused by stress. Equally important are the behavioural attributes; peaceful, social fish are often best although this does depend on the overall community. A factor often overlooked is the fish's ability to adapt to new surroundings, not in terms of water conditions but simply the type of décor and the present fish population.

Some fish, particularly large or active fish will quite happily settle into a tank with little décor and no tankmates. Other fish will find this distressing and despite perfect water quality will soon try to hide, stop feeding, and succumb to illness. Many fish use the fact that there are other fish in an aquarium as a sign that the environment is safe. So a good first fish species would be one that is hardy, disease resistant, sociable, adaptable, active and confident.

The problem with Guppies

Now we can look at getting rid of some old habits and where better to start than with the infamous guppy. The guppies of old were tough as old boots and would survive almost anything, However, intensive breeding and a quick succession of generations has led to the vast majority of guppies available nowadays having the ability to die at the drop of a hat. Inbreeding, a lack of natural selection and the comparatively sterile aquarium environment have all taken their toll on the guppies natural immune system; the slightest hint of bacterial infection can now wipe out an entire tank of guppies. All is not lost however, in a well matured and stable tank, a good bunch of guppies should do fine for their usual lifespan of around 18-24 months. In a new aquarium however, there are simply too many 'triggers' for disease to consider the guppy as a good first fish. Other popular livebearers including swordtails, mollies, and platies also suffer similar problems and are particularly prone to skin-related diseases. Specimens in full health however are normally fine as a first fish and the occurrence of disease can be partially prevented by the correct use of aquarium salt.


A close second for popularity verses unsuitability is the humble neon tetra, again a popular fish for new aquariums. Neons are lovely little fish, but they do tend to be a little timid, are sensitive to fluctuating conditions and are prone to disease problems in new aquaria. A well-established shoal of neons can live for many years but if introduced too early, you will be lucky to get a few months. Many other small tetras are also a little timid as first fish in new aquaria, unless they are introduced in large shoals of ten or more, but are ideal as a second or third introduction.

Feeding problems

Catfish are next in line; it is usually the popular Corydoras sp. group of catfish that are often chosen for new aquariums. The reason why these are not suitable as first fish is a little complicated as the fish themselves will settle into a new tank with no social, disease or confidence problems. The problem is that to keep these fish properly they need to be kept in groups and given a varied diet of sinking foods and frozen or live foods such as bloodworm. In a new tank, feeding a whole group on these high protein foods creates the ideal conditions for an overdosing of waste product and a 'system crash' resulting in high ammonia and nitrites.

Other heavily bred species

It is worth mentioning that in recent years the Dwarf Gourami Colisa lalia and Honey Gourami Colisa sota have undergone a change similar to that of the guppy with new striking colour forms emerging along with all the associated problems of intensive breeding. These small gouramies also suffer from a nervous disposition making them unsuitable for new aquaria and best left for a month or two before being introduced.

Popular fish not suitable as a first fish
Neons | Guppies | Small Gouramies | Scavenging loaches, algae eaters, or catfish

So which fish are the best first fish?

To start with the case for barbs should be fought, which always seem to be continually tarred with the undeserved 'nippy and aggressive' brush. Without doubt this is largely due to the Tiger Barb Barbus tetrazona that can be very nippy and troublesome, but experience shows that this only occurs when too few are kept together and they are mixed with the wrong fish. For instance if a small group of tiger barbs are kept with colourful long finned fish and the long fins get nipped beyond recovery the question has to be was it the barbs or the long-finned fish which should not have been introduced? Excluding the larger barb species, barbs in general are very good first fish having all the attributes mentioned earlier and whilst not as colourful as some fish, they certainly do have personality and style.

Colour and size

If you do want something with a little more flair then the rainbowfish family are well worth a look. These peaceful fish have hardly any demands, although they often prefer harder water, and will mix well with other active fish. Most rainbowfish only develop their full colour once they have been settled in an aquarium for a few months so its important to see their potential when they may look a little drab at the point of purchase.
The larger Gourami species are good first fish for aquaria with plenty of plants and hiding spots. Pearl and Moonlight gouramies are ideal for most aquaria whilst the Opaline, Gold and Three-spots are suitable providing they are kept in a minimum group of 5. Because Opaline, Gold and Three-spots are all the same species the group can be a mixture but if kept in small numbers one will become dominant and bully either all the others or pick on the weakest of the group.

Fish generally suitable as 'first fish'
Barbs | Larger Gouramies | Rainbowfish | Shoals of larger Tetras | Danios

Tips for choosing first fish

Choose several varieties of fish you like, make sure they will all get along (try using the Think Fish Compatibility Checker), and then find out which are the hardiest. This is a better method than setting your heart on a particular fish species when another may be a better first introduction.

Avoid fish that have specific feeding habits, extra food types will add more waste to the aquarium, which may affect water quality. For the first 6-8 weeks your fish should be fed a simple flake food, after this period the diet should be steadily adjusted to include as much variety as possible, at this point fish with more specific feed requirements can be added.

Don't buy to many at once. Although it can seem a little pointless looking at an almost empty aquarium it is vital that you stock slowly, or you risk loosing large numbers of fish to disease and bad water quality which may take ages to sort out. The amount and frequency of fish you introduce depends on the size and type of your aquarium and filter. A general rule is no more than six small fish every seven days.

Ask how long the fish you have chosen have been in the shop. Any fish that have only been in the tank for a few days should be avoided, the extra stress of being moved twice in the same week and entering a new aquarium is likely to cause problems.

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