I've kept many Mudskippers over the years and can be an interesting a fun fish to keep! There are over 30 species of them, but only about three or four species are usually found available for sale. Most are brackish water fish and usually very tolerant of water conditions, BUT good water conditions should always be maintained! All Mudskippers are territorial, although the degree of aggression varies genus to genus and also fish to fish. The largest are the African Mudskipper, which in my opinion have the best color are also the most aggressive and largest which can grow to 10 inches! I have been able to keep two together in a 40 breeder. Don't EVER mix different species of mudskippers together! Other commonly found available are from India and Indonesia which some species of these can grow to about 8 inches. Mudskipper have been said to be "walking stomachs" and will eat ANYTHING in front of there face including each other if they can. All species of Mudskippers need both water and "land" to survive. Although it varies from species to species. I've done best with them in a "terrarium" type setting with live plants with one male and one or two females.