Longhorn Cowfish

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Sep 22, 2006
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North Wales
Common Name(s) - Longhorn Cowfish, Longhorn Boxfish

Scientific Name - Lactoria cornuta

Family - Ostraciidae

Maximum Size - wild around 20", in home aquariums up to 16" (usually less)

Minimum Tank Size - 180 UK gallons, 681litres

Origin/Habitat - Indo-Pacific, East Africa, Red Sea, Tuamotu Archipelago, Polynesia, Lord Howe Island, Southern Japan.
Lives in weedy areas, algae beds and in sea grasses, near rocks or reefs. Juveniles often swim into sheltered river mouths and can live in
brackish water.
Depth of range 1-100metres

Care - The longhorn cowfish is an easily startled fish and can injure itself by bumping into the glass tank walls or can become stuck in the rockwork. Care should be taken to prevent it becoming startled. When stressed or close to death they exude a powerful toxin which is capable of killing all the inhabitants of it' tank, including the cowfish itself. As they mature they become more sensitive to changes in lighting, so care must be taken when turning aquarium lighting on and off. Longhorns have also been known to jump out of the tank when startled so a hood is advisable.
This is a peaceful fish and should not be housed with any overly aggressive fishes or fast swimmers who will out-compete the slow swimming longhorn at feeding time. Longhorns should not be housed with cleaner wrasses. It is common for the longhorn to be pestered to death by the wrasses chasing them in order to clean them. This is not generally considered to be a reef safe fish as it will eat inverts as it gets bigger, although as yet mine has never bothered anything in my tank. They are charming fish with bags full of personality. They definately recognise their owner and will follow your finger around the glass and beg for food by staring at you. They are also very inquisitive and need lots of stimulation in their surroundings. If something new is added to the tank,mine will spend hours studying it.
Longhorns are really quite slow, sedate swimmers and don't like too much flow. Mine can often be found sitting alongside my powerhead where the flow is at it's lowest. Good water qualiy is very important for these fish. They are particularly susceptible to Cryptocaryon and Lymphocystis

Feeding - In the wild Longhorn Cowfish forage for benthic vertebrates (crustaceans, mollusks, urchins, sea cucumbers etc.) by blowing a jet of water into the sand. In the home aquarium Longhorns should be fed a mixed diet of meaty foods such as mysis and chopped fish/octopus, but also should be provided algae based foods. Marine mix is perfect for these fish. They will graze on the live rock all day and love to eat polychaete worms, often decimating the whole population. As they begin to equate their food with the water's surface you may find they will spit water at you during feeding, a throwback to their method of feeding in the wild. Care must be taken to avoid feeding Longhorns floating foods. If they feed from the surface they easily ingest air which causes them major problems.It can be useful to turn your powerheads off at feeding time to be sure the longhorn is getting enough food.

Sexing / Breeding - It is difficult to tell the sex of Longhorn Cowfish as there is no sexual dimorphism. In the wild a single male will have a small group of females who live within his territory. There is an elaborate courtship followed by the release of a number of eggs. The resulting larvae are pelagic. They are not known to breed in captivity.

Comments - The main feature of the Longhorn Cowfish are it's horns. The two horns are a defense mechanism making them difficult for a predator to swallow. As the Longhorn grows, the horns become shorter.

Notes - Please note, the Longhorn Cowfish is HIGHLY TOXIC when stressed. It's skin is contains ostracitoxin which is released when the fish is stressed or close to death. Under no circumstances should any shipping water be allowed into the tank during acclimitisation. If the Longhorn appears stressed or sick it must be removed IMMEDIATELY. If any toxins are released into the tank it may be possible to minimise the effects with large amounts of carbon filtration and frequent, large water changes. However it is unlikely to prevent some losses. If the toxin is released it will most likely kill every living thing in your aquarium. If the fish must be removed for tank maintenance it should be placed in a bowl on it's own.



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