How to set up a quarantine tank


Jeremy Gay shows how you can easily create your own quarantine tank on a budget.

A quarantine tank will save lives. Fish can be slowly acclimatised and screened for infectious diseases, sick ones can be medicated and you can even breed in one!

The components for one of these are the most important purchases you’ll ever make — and this complete example would set you back just over £62.

The tank

The legendary Clearseal 46 x 25 x 25cm/18 x 10 x 10” aquarium has been used in the set-up shown above, complete with plastic hood and polystyrene tile cushioning underneath. It’s large enough to quarantine fish up to about 10cm/4” in length and small enough to be portable.

You don’t want a light in the hood as bright light will stress sick fish and break down medication. The lid also prevents irritated fish from jumping out.

Price: £22.99

Air-powered sponge filter

This provides gentle mechanical and biological filtration, along with extra aeration at the same time. Sick fish can’t swim against strong currents and will tire quickly. No provision for chemical media means that you won’t accidentally remove a medication with carbon either.

Price: £5.99


Essential for tropical fish, place a combined heater/thermostat diagonally across the rear tank glass to spread heat evenly.

Choose a model that’s easy for you to adjust and that can heat up to more than 30°C/86°F — a key factor in fighting parasites like whitespot.

Price: £19.99

Flower pot

Don’t underestimate the usefulness of this piece of earthenware. Cave spawners will breed on it and shy fish will hide in it. It’s also useful for sick fish, as they can back up into it and feel more secure.

It won’t affect water quality or medications either.

Price: 60p


This is essential for at-a-glance temperature monitoring. Heat can be an effective weapon in fighting parasites, so this way you can ensure that everything in the tank is as it should be.

Price: £2.99

Plastic plants

These give cover to nervous fish. The designs here are pre-weighted by a resin base. They are fine with medications and won’t affect water quality by dying off and polluting the aquarium.

Price: £10

Bare bottoms

Quarantine tanks are left bare for a reason. Part of the life cycle of some parasites involves a stage that lives in the substrate — so by having bare glass it will interrupt reproduction and, in the case of large parasites or worms, will help you spot them on the tank base.

Get a test kit

Fish won’t get better in poor water so it must be monitored at all times. Run your quarantine water as you would in your main tank, making sure that the water conditions are ideal for the species housed. Optimum water quality will aid recovery.

How can I avoid new tank syndrome?

This question often arises when quarantine tanks are discussed. If you maintain one with no fish the bacteria will die off through lack of food — causing you problems when you do eventually add fish.

Prevent this by placing the sponge of the filter inside a filter in your main tank. Then, if you need the quarantine tank for new fish, sick fish or breeding, move the mature sponge over to instantly provide filtration.

If the fish is sick, when you have finished treating, either sterilise or replace the old sponge with new and place back inside the main tank’s filter for re-maturing.

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