Longhorn Cowfish

Longhorn Cowfish

The Longhorn Cowfish are usually discovered within the reefs of the Indo-Pacific, and most commonly in the lower current waters. The cowfish's body has a yellow base and is covered with white and blue dots, and is occasionally referred to as the Yellow Boxfish; however, the Longhorn is not to be confused with Ostracion cubicus, commonly called the Yellow or Polka Dot Boxfish. In the wild, it is not uncommon to see a 18-22" specimen, while in the aquarium the Longhorn Cowfish tends to be dramatically smaller - 15" or less.

If it is possible, you should try to add the Longhorn Cowfish to the home aquarium first before adding more aggressive and active fish. Additionally, it should be noted that this Cowfish needs to be housed in a relatively large tank, decorated with a live rock for algae grazing. Furthermore, caution needs to be taken when adding this fish to your tank if you are looking to maintain tubeworms, as this fish is known to eat them. 

Longhorn Cowfish can be very long lived when housed correctly. However, it must be acknowledged that the Cowfish has poisonous skin, and when it is threatened, it can be known to ex-spell toxins that can cause critical  damage to other fish in the tank. 

The Longhorn Cowfish is an omnivore and must be offered a range of vegetable and meaty foods. Furthermore, it is important to consider that these fish are very cautious eaters and do take their time, so issues may occur if it is housed with more aggressive and active eaters. 

Minimum Tank Size500 Litres
Care Level: Difficult
Temperament: Peaceful
Reef Compatible: With Caution
Water Conditions: 72-78° F, dKH 8-12, pH 8.1-8.4, sg 1.020-1.025
Max. Size: 1' 8"
Colour Form: White, Yellow
Venomous: Poisonous When Stressed or Dies
Diet: Omnivore
Origin: Indo-Pacific
Family: Ostraciidae

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Easy to Care For
Easy to Feed
Peaceful with Others
Reef Safe
Invertebrate Safe

  1. The Cowfish Longhorn is extremely friendly and will eat out of its owner’s hand. It requires pristine water conditions, or it may succumb to disease. Ultra-Violet Sterilizers are recommended with Cowfish. Also keep carbon in the tank or filter at all times to prevent die offs due to ostracitoxin release.

  2. This isn’t a beginer’s fish, but it does seem easier to keep than some people make it out to be,(or maybe I’m just used to keeping difficult fish by now). One thing that seems to help entice this fish to eat is feeding it pinches of mysis shrimp by hand along with sheets of nori. Also, do make sure never to expose this fish to air,(bag it under water, feed it below the surface), any trapped air inside this fish will kill it. This fish has wonderful personality, is increadibly smart, and seems to learn to recognise its owner.

  3. Great fish with a great personality. They are pretty fast at growing too, so make sure you have enough room for that. I have had mine since it was 1″ and it is now about 8″ and eats very well. It is a peaceful fish and is definitely one of the most unusual which is why I love it. I have heard lots of different opinions about it being poisonous, some say it is, some say it isn’t, but personally I would always use a container and not a net when moving it, just incase.

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