FAQ: Grooming for fish

A brown, easily wiped film on the glass and decorations is often diatoms, which are common in new tanks. They usually disappear once the tank settles, and meanwhile you can simply wipe or siphon them away.

They help reduce algae but do not remove the cause if there is too much light or nutrients. Many algae eaters also cannot live on algae alone and need extra food, and they must suit the size of your tank.

They can reduce algae for a while but do not fix the cause, and some harm plants, shrimp or snails. Decaying algae also lower oxygen levels. If you use one, follow the label strictly and watch your animals.

Fast-growing plants use the same nutrients and light as algae, leaving less for them. Floating plants also shade the water a little. A well-planted tank usually has less algae.

These dark tufts cling tightly, so it is easiest to take decorations and rocks out and scrub them with a brush; hard decorations can be scalded with hot water. Affected plant leaves are usually trimmed off. Unstable conditions often encourage them, so review the lighting and how regular your maintenance is.

Cyanobacteria form a slimy blue-green or dark green film with an unpleasant smell. Siphon it out, change water more often, cut back feeding and lighting and improve water flow. If it keeps coming back, ask an experienced aquarist.

White limescale lines form as hard water evaporates. You can scrape them off with a scraper, and outside the tank or in an empty tank wipe them with a vinegar-dampened cloth and then rinse well with clean water. Do not use acids or cleaners in a tank with fish.

A damp microfibre cloth and clean water are usually enough. If you use a cleaner, spray it onto the cloth rather than the glass and choose one without ammonia, so no drops or fumes get into the water.

Never inside the tank. Outside it is possible, but only sprayed onto a cloth and away from the water surface, because many window cleaners contain ammonia or other substances harmful to fish. Water and a microfibre cloth are safest.

Condensation, limescale and dust build up on the lid and light cover and reduce the amount of light. Switch off the power first, wipe with a damp cloth and limescale with a vinegar-dampened cloth, then rinse and dry everything before putting it back.

The net should be clearly larger than the fish so it fits without bending, but not so large that it cannot get between decorations and plants. If you keep fish of different sizes, two nets of different sizes are handy.

A fine mesh net suits shrimp, fry and live food, but it moves more slowly through the water. A coarser net moves faster, but fins and spines tangle in it more easily and small fish can slip through.

Use two nets: gently guide the fish with one into the other held still. Do not chase the fish around the whole tank for long, take out a few decorations if needed, and dimmed lighting calms the fish.

Catfish and other fish with spines or long fins get caught most often. A soft fine-mesh net suits them better, or you can coax the fish into a plastic container. Free a tangled fish slowly while keeping it in the water.

Yes, many aquarists coax the fish into a clear plastic container or bag. This handles it more gently, keeps it in the water and protects its slime coat, which especially suits fish with spines or long fins.

Rinse the net after every use and let it dry, because drying kills many microorganisms. If there has been disease in the tank, you can use a disinfectant made for aquarium equipment according to the label and then rinse very thoroughly.

Yes, if you keep several tanks or a quarantine tank. Shared nets, siphons and buckets can carry pathogens and snails from one tank to another. Separate tools are easy to tell apart with colour coding.

Replace the net when the mesh tears, wears thin or starts to fray, or when the frame edges become sharp. A hole lets fish escape and sharp edges can injure them.

A net makes it easy to scoop floating leaves, leftover food and excess floating plants off the surface. That means less organic matter sinks to the bottom and rots.

You can lift the film by laying a clean paper towel on the water for a moment or by using a surface skimmer. To stop it coming back, angle the filter outflow so the surface moves, and do not overfeed.