Cowfish.

dont they get too big for 10 gallons?

what one max out at 4-5 inches? the thorn back gets to be about 6 inches but shouldn't be kept in less than a 50 gallon. they are very sensitive to everything and need much stability. plus in an aquarium of that size if they release their poison they will surely die as if they were in a lager system where it would defuse. i wouldn't do the 10 gallon. all other commonly sold species get to be 18+ inches. and the thornback, Lactoria fornasini isnt that common in the trade and is easily confused with the long horn cowfish.

I have never heard of something called a "Decent" sized 10 gallon.

Everything I've read about them state a minimum of 120 gallon tank!

Helmet cowfish and thornback's are the two smallest species and these max at 5-6 inches. 10 gallons is way too small. Thornbacks and helmet cowfish are also the least likely to omit toxins, with no documented deaths by toxins that I have found from either of these species. Ostraxation is most common in the hawain blue cowfish and the longhorn. I wouln't hesitate to put a thornback or helmet cowfish in a tank with other life due to toxin fears, but they will eat snails and have been known to nip at corals and can't handle much flow in the tank.

www.cowfishes.com is a great resource if your interested in these guys, awesome fish.