Angler Fish

The anglerfish sold for home aquariums are frogfish, from the family Antennariidae, not the deep sea anglerfish seen in nature documentaries. With lumpy, camouflaged bodies and a small lure on the head, they look nothing like typical reef fish. They also bring real challenges. They eat other fish, some refuse anything but live food, and species can be hard to identify even though size and care vary between them.

These shallow water species do not need specialised pressure conditions. Many commonly traded species come from tropical reefs and rocky areas, though others live in subtropical waters or among sand, rubble and floating weed. Some can be kept successfully by experienced marine fishkeepers, provided their feeding and housing needs are met.

Choosing and Buying a Frogfish

The warty frogfish, Antennarius maculatus, reaches about 15cm, while the giant frogfish, Antennarius commerson, can reach roughly 38cm. Get a reliable species identification, then check adult size and recommended aquarium dimensions in a reputable care source. No single tank size suits every frogfish. They are not very active, but they still need adequate floor space, plus enough water volume and filtration to cope with the waste from large meals.

Before buying, check that:

• the species is confirmed
• the fish feeds in front of you, and you know exactly what it accepts
• the lure is intact and the skin looks healthy
• breathing looks normal

Many traded frogfish are caught from the wild, so ask about origin and collection. OATA, the Ornamental Aquatic Trade Association, publishes guidance that many UK shops follow, though this alone does not guarantee a shop's standards. Under the Animal Welfare Act 2006, owners in England and Wales must meet their animals' needs. The Animal Health and Welfare (Scotland) Act 2006 and the Welfare of Animals Act (Northern Ireland) 2011 set similar duties.

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Tankmates

Tankmates pose a particular risk. Frogfish are ambush predators with huge mouths and stretchy stomachs, and they may try to swallow surprisingly large prey, which can injure or kill both fish. Larger companions may bite the frogfish, damage its lure or stop it feeding. Being bigger than the frogfish does not, by itself, make another fish suitable, so a tank housing a single frogfish is generally the safest arrangement.

• Keep one frogfish on its own. Cannibalism is a serious risk, especially where individuals differ in size.
• Small shrimps, crabs and other crustaceans are likely to be eaten. "Reef safe" and "marine community" are not the same thing.
• Fin nipping fish may stress a frogfish or steal its food.

Your situation may be slightly different. ask a question below ↓ and our editorial team will reply with our advice.

Setting Up the Aquarium

The aquarium must be fully cycled before the fish arrives. Frogfish need shelter, secure resting places and effective biological filtration. Live rock provides these, but properly matured aquarium rock and other biological media work too. Make rockwork stable and leave open space so you can watch the fish and reach it at feeding time. Avoid abrasive decorations, as the skin scratches easily. A sand bed is optional for many commonly kept species.

Published guidance for commonly kept tropical species often falls around 24 to 27°C and a specific gravity of 1.024 to 1.026, but check this against your species. Test pH, ammonia, nitrite and nitrate regularly and make routine partial water changes. A protein skimmer helps but does not replace biological filtration or maintenance. Provide good circulation and oxygenation, with sheltered resting spots rather than a strong jet aimed at the fish.

Quarantine new arrivals separately before they join an established system. Handle them as little as possible and ask for frogfish specific transfer advice, since ordinary netting may be unsuitable.

If you see cloudy patches, redness or frayed skin, check water quality promptly and contact a vet experienced with fish, particularly if a lesion spreads, the fish deteriorates or breathing becomes abnormal. The Royal College of Veterinary Surgeons' Find a Vet service can help. Call first to confirm the practice treats ornamental marine fish, as exotics services do not always include fish.

Feeding

A frogfish waves its lure to attract prey, then strikes fast and swallows it whole. Many newly bought fish only take live food. Some can be trained to accept thawed food, but success is not guaranteed, so do not buy a fish that depends on live food unless you have a suitable, sustainable way to supply it.

Thawed options include marine fish such as lancefish or silversides, whole prawns or shrimp, and pieces of squid or mussel. Use raw, unseasoned food of a suitable size, bought and stored safely. Chunks of muscle meat are not equivalent to whole prey and should not make up the whole diet. Nutritional value, including thiaminase content, varies by prey species, so a varied marine diet is safer than one staple. Offering food gently on a feeding tool can prompt a strike, but avoid exposed sharp or rigid tips the fish could bite.

Avoid goldfish and minnows. Some common feeder fish have poor nutrient profiles or contain thiaminase, and live feeders can bring in disease.

Overfeeding causes obesity and fouls the water. Frequency depends on species, age, body condition and portion size, and adults usually need food less often than young fish. Avoid oversized meals as well as frequent ones.

Never release a frogfish into the wild. If you can no longer keep it, ask an aquatic shop or fishkeeping club about rehoming. Above all, confirm the species, its adult size and what it eats before you buy.

The Next Step

Now that you have read through the advice above, you might want to put it into practice. Our Aquarium Stocking Calculator lets you calculates safe fish stocking levels based on tank size, filtration, and species bioload. Try it now →