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Resident Cowfish!

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Any fans of these endearing aquadogs here??


My main motivation to upgrade to a large system was primarily to keep a Cowfish in the Long-term. I’ve done plenty of research and according to many sources this species(Lactoria Cornuta, as well as other boxfishes and cowfishes), is quite a handful to successfully care for in captivity.


My experience has been contrary to these sources though, as I’ve found more success with this fish than with even common Ocellaris clowns(that I can never seem to keep alive for some reason, and I’m not even joking. Must be the curse of Nemo lol)despite it being listed as an “expert-only fish”.


That said, the most important things to note when deciding to get a Cowfish for your aquarium are definitely:


1) Lower flow, or at least areas in your tank with significantly lower flow,(especially for smaller specimens) due to their slow locomotion.


2) Tankmates

Since most Cowfish are even slower than Boxfish(the latter can propel themselves forward faster but lack the ability to “hover” while simultaneously turning 360 degrees; something which Cowfish can do), they are easily outcompeted during feeding and may require spot-feeding.



While most LFS sell them when they are cute juveniles not more than 3 inches long, these guys can grow to a maximum of half a meter. Of course, that’s in the wild- but odds are if you have anything less than a 5ft/125 Gallon tank, keeping one may not be the wisest choice in the long run.


4) Filtration

I’m sure most people in the hobby have heard that members of the Cowfish and Boxfish family can secrete a poisonous toxin via their skin into the water when under stress. I wouldn’t go so far as to say it would “nuke” your tank(having an anemone get stuck and die in a powerhead is actually worse), but having a good filtration system in conjunction with running a healthy dose of activated carbon will help to counteract these tendencies. If you have experience with a reeftank, think of their “toxic mucous” as something akin to the also toxic mucous expelled from corals such as leathers. They are not too different, but having a larger system will also lessen the odds that any harmful toxins that may be secreted by a Cowfish when under stress could be a potential threat to the well-being of your tank and it’s inhabitants.

*Source: personal experience when a 2-inch juvenile Cowfish died from getting sucked and stuck in my overflow, with no other casualties in the tank. Then again it was only a small specimen, so it’s toxins were probably not as lethal.


As with any fish, when provided with a suitable environment, Cowfish aren’t all that hard to keep. In fact, they are likely more Reef-safe than most angelfishes, so you’re not limited to a FOWLR system. Most Cowfish will have a curious “taste-test”( have olfactory glans which allow them to even “taste” with their skin layer”) in new items but typically do not harm corals. One should be wary to keep them with smaller sessile invertebrates like small clams/scallops, shrimp and snails, though.


Watch out for that bite!

While not as strong as the bite of a puffer, cowfishes and boxfishes can inflict a painful bite should they mistake your finger, hand or arm for food, and it only gets more painful the larger they get. They have cone-like, O-shaped mouths, but don’t let that fool you- the insides of their mouths are filled with needle-like teeth that point outwards and can inflict wounds similar to that of an injection.


I would say that what makes Cowfish a pleasure to keep is how endearing they can be when they come up to the front of the tank in a puppy-like manner to greet you or curiously see what’s going on, or spit water at the surface of the tank to get your attention, probably in a bid to beg for food. They are certainly not a shy fish. Depending on how you feed them, will associate hands or prongs or certain actions you do in front of your aquarium with feeding time, so be aware of that(mine likes to come near to my hand/arm when I have them in the tank because he associates them with food because I’ve been hand-feeding him since he was in quarantine)



As with all fishes, Cowfish are as susceptible to common parasites like marine ich/whitespot disease. While not as likely to carry them unlike tangs, they are probably even more at-risk of succumbing to parasites that other fish die to their poor locomotion(they are slow swimmers and their structural anatomy is like that of a Seahorse; they can’t wiggle around to shake or scratch parasites off), and are this easily overwhelmed when parasites take hold. Thankfully, they do tolerate copper treatments.


Contrary to popular belief, they are a generally hardy fish, but due to their large surface area and being slow swimmers, they don’t do well in high-flow tanks with mostly one-directional type currents and little cover. Feeding is not as much of an issue as with boxfish, as Cowfish are not picky and will gladly take pellet food, algae sheets, market prawns and even lettuce when offered. The trick is having enough food such that they are not outcompeted by their usually faster tankmates- in which case spot-feeding may be another solution, especially during the earlier stages of its introduction into your main display.




Sent from Singapore Reef Club mobile app




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Thanks for sharing bro! Btw is ur tank a nano for your cowfish?  Sent from Singapore Reef Club mobile app      




Thanks! Like I said I upgraded to a large system so my setup is definitely not a nano. IMO it is not feasible to keep a Longhorn Cowfish(though there are occasionally other smaller Cowfish species, though much rarer, that get shipped in)Long-term in even the largest of nano tanks as they grow to an average of 40cm or more in captivity, which is well above any nano tank capacity. If you do, you will find yourself needing to upgrade to a larger tank or get rid of it when it begins to rapidly grow in size(they are slow growers at first when 1-3inches but their growth rate really speeds up after that when they begin to eat a lot more). They are slow swimmers though, so it wouldn’t be impossible if you can’t go any larger than a 120 Gallon tank. I’d say a minimum of 120 Gallons as far as tank sizes go.  Sent from Singapore Reef Club mobile app     





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Ah okay ! Saw that you are keeping it in a nano previously, was tempted to try too Will reconsider about it now haha  

Sent from Singapore Reef Club mobile app



Yes I was, in fact my first Cowfish was caught myself from a local shore, and since I’ve been keeping saltwater tanks for a Long time on a Budget, I decided to keep it in my old 2ftx1t before deciding to upgrade. And since then my love for this fish has brought me here today, where I find myself maintaining a full 125 gallon reef tank! Sadly I’ve lost that original fella during a marine velvet outbreak, the second to a tank crash and the third to an overflow. Making sure that my current one receives the utmost care hahaha  


Sent from Singapore Reef Club mobile app



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