FAQ: Tank Decor for fish

Yes, for territorial fish decor helps divide the tank into separate zones and break lines of sight, which cuts down on fighting. Use rocks, roots and plants to create several distinct territories, each with its own hide.

Shells and coral are made of calcium carbonate, so as they dissolve they raise water hardness and pH. That suits hard-water fish, but do not use them in a soft-water tank, and clean and boil them thoroughly before adding them.

Yes, most metals corrode or dissolve in water and release ions that harm fish, and copper is especially dangerous to shrimp and snails. Do not put coins, nails or ornaments with metal parts in an aquarium, and use only stainless steel or plastic for fixings.

Glass is inert, so glass pebbles made for aquariums do not change the water. But they are slippery, debris collects between them, plants cannot root in them, and chipped pieces can be sharp.

Aquarium-safe silicone with no anti-mould additives and cyanoacrylate gel glue are suitable for aquarium decorations. Let the glue cure completely, as the manufacturer directs, before submerging the decoration.

It is not advisable, because building and bathroom silicones often contain fungicides and other additives that harm fish. Use only silicone made for aquariums or one whose description clearly states it is aquarium-safe.

Some aquarists make 3D backgrounds from polystyrene or polyurethane foam coated with cement or epoxy resin, but a fully cured coating is essential. Uncoated materials can leach chemicals, so beginners are safer buying ready-made aquarium backgrounds.

Plastic and resin decorations made for aquariums use materials suited to permanent immersion. Plastics of unknown origin, especially soft or smelly ones, can leach plasticisers or dye, so it is best not to use them.

Unglazed clay pots without paint or varnish are inert and often used as hides or spawning sites. Rinse them well before use, sand down sharp edges and make sure the drainage hole is not one a fish could get stuck in.

Clean, unpainted PVC pipes are used as simple hides for catfish or loaches, especially in breeding or quarantine tanks. Rinse them well and smooth the edges, and if you want a more natural look, choose ceramic tubes.

Scrub decorations from another tank and scald them with hot water, or let them dry out for a few days. If you use disinfectants, follow the maker’s directions, rinse very thoroughly and neutralise chlorine before putting them in the aquarium.

Yes, wet decorations, rocks or roots from another tank can carry parasites, snail eggs or pathogens. Clean and dry them before moving them, and if you see signs of sick fish, contact a vet.

They can, if decor blocks the filter intake, redirects the flow or touches the heater. Leave free space around the equipment so water circulates and the heater does not touch the glass, rocks or substrate.

Decorations usually only need cleaning when algae or dirt shows on them, typically every few weeks during water changes. Cleaning too often and too thoroughly washes off beneficial bacteria, so do not clean all the decor at once.

Take the decoration out and scrub it with a brush or toothbrush in tank water or warm tap water, without detergent. Tough algae can be scraped off rocks with a plastic scraper, and snails help keep decor clean inside the tank.

Very dilute bleach is sometimes used on heavily covered artificial decorations or rocks, but it must be rinsed off very thoroughly and the chlorine neutralised. Wood and porous materials should not be cleaned this way, as they soak up the bleach.

White lime deposits on removed rocks or decor can be dissolved by soaking them in vinegar or citric acid solution and scrubbing. Rinse the decor very well with clean water afterwards so no acid gets into the tank.

It is not advisable, because dishwasher detergents and their residues harm fish, and the heat can warp plastic or resin decor. Wash decorations by hand with warm water and a brush, with no detergent at all.

No, it is better to clean them in rounds: beneficial bacteria live on decor, so cleaning everything at once can upset the biological balance and raise ammonia. At each water change clean just one or a few decorations.

Scrub the driftwood with a stiff brush in tank water or warm water without detergent, and clear algae from crevices with a toothbrush. If needed the wood can be scalded with hot water, but remove any plants tied to it first.