FAQ: Supplies for fish

Floating plants and water lilies shade the surface and reduce algae, submerged plants produce oxygen, and marginal plants absorb nutrients. It is often advised that plants cover about a third of the water surface.

Remove leaves and larger debris regularly, maintain the filter as the manufacturer says, and do a major sludge clean-out once a year, usually in spring or autumn. Draining all the water is normally unnecessary.

An air pump helps in hot weather, when warm water holds less oxygen, in heavily stocked ponds and in winter to keep a hole in the ice. A fountain or waterfall also helps oxygenate the water.

Yes, but larger amounts of tap water should be treated with a pond conditioner that neutralises chlorine. Rainwater from a roof can be contaminated, so use it with care.

Changing about 10–25% of the water every week or two is usually recommended. The exact amount depends on the number of fish, the plants and the nitrate level, which you can check with a test.

Not recommended. Replacing all the water at once shocks the fish with sudden temperature and parameter changes and upsets the bacterial balance, so it is better to change a small part regularly.

Clean the substrate with a gravel vacuum, which sucks up debris between the stones during a water change. Do not clean the whole floor at once, and work carefully around plants so you do not damage their roots.

Useful items are a gravel vacuum, a bucket used only for the aquarium, a glass scraper or magnetic cleaner, a net, long tweezers and plant scissors. Do not use buckets or sponges that have been used with household chemicals.

Clean the glass with a magnetic cleaner, a blade scraper or a special sponge. Clean acrylic tanks only with tools made for acrylic, because metal blades scratch them.

No, residues of household cleaners are poisonous to fish. The outside glass can be wiped with a damp cloth, and the inside surfaces only with water and tools made for aquariums.

Water evaporates naturally, especially from a warm tank without a lid. Top up with treated fresh water, since salts and minerals stay in the tank; a lid greatly reduces evaporation.

Most filters only need rinsing every few weeks or when the flow drops. Cleaning too often or too thoroughly removes the beneficial bacteria, so the filter does not need to be spotless.

Warning signs are a bad smell, cloudy or yellowish water, fast-growing algae, fish gasping at the surface and faded colours. Test the water and review your feeding and water-change habits.

Daily you only need to feed the fish and check the temperature and equipment, and every week or two change some water and clean the substrate and glass. For a medium tank this usually takes about an hour a week.

Ongoing costs are food, water conditioner, filter media, tests and electricity for the filter, heater and lighting. The heater usually uses the most electricity, especially in a cool room.

Compare prices across shops, especially for more expensive equipment, and look at the price per kilogram or litre when buying food or water care products. Larger packs pay off only if you use them up before they expire.

A used tank can be a good choice if the glass has no cracks, the seams are intact and it does not leak. Before using it, fill it and leave it for a few days on the floor or outdoors, and check equipment such as the heater separately.

Check what tank volume the equipment is for, its dimensions, power, noise level and whether spare parts such as filter sponges are available. Tanks and substrate are heavy, so factor in the delivery cost too.

Not always. What matters most is that the equipment suits your tank size and your fish’s needs; pricier models are often quieter, more precise or larger, but a simple tank may not need those features.

We collect the shops’ prices about every day. Each product shows when its price was last checked.