[1] The head is subcylindrical and flattened dorsoventrally, and slightly concave in the area between the tip of the snout to just behind the eyes.

The first dorsal fin (with five to six rays) is arched and originates from the highest point of the back of the fish.

[3] Crazy fish are drably colored, with the body predominantly mottled dusky gray to olive green.

Five or six irregular dark transverse bands are present, obscured somewhat in the front, but distinct in the rear half of the body.

[9][10] The crazy fish was first described by the Scottish naturalist Francis Buchanan-Hamilton in 1822 from a specimen recovered from the Ganges River near Calcutta, India.

Hamilton is believed to have derived the name from the Indian word butis, decorative circular designs on sari fabric, probably referring to the coloration of crazy fish.

[12] Other common names of crazy fish include upside-down sleeper, crimson-tipped gudgeon,[1] duckbill sleeper, crocodile fish, flat-headed gudgeon, pointed-head gudgeon, and bony-snouted gudgeon in English;[13] eendbek-slaper in Afrikaans; kuli (কুলি) in Bengali; kuonotorkkuja in Finnish; butis à épaulette noire in French; Spitzkopfgrundel in German; pasel in Ibanag; nyereh, ploso, puntang, belosoh, belontok, ubi, and ubi muncung itik in Indonesian and Malaysian; bloso-watu in Javanese; jǐ táng lǐ (嵴塘鳢) in Mandarin; vaneya in Sinhalese; bukletkhaeng (บู่เกล็ดแข็ง) in Thai; and cá bống cấu, cá bống đầu dẹp, and cá bong trân in Vietnamese.

[1][14] Crazy fish inhabit brackish and freshwater habitats near the coast, but they can sometimes be found upriver.

They are demersal fish, usually found near the muddy bottoms of lagoons, estuaries, and mangrove forests with abundant vegetation.

[1][2][15] Crazy fish has a wide distribution range: west from East Africa to as far east as Fiji, north from the South China Sea and south to Australia and New Caledonia, including islands in the Indian and Pacific Oceans.

[1] Countries where it is found include Australia (New South Wales, Northern Territory, Queensland, and Western Australia);[16] Brunei Darussalam; Cambodia, China (Guangdong, Guangxi, Hainan, Hong Kong,[17] and Macau); Fiji;[18] India (including the Andaman and Nicobar Islands);[19][20] Indonesia;[15] Japan; Kenya;[21] Madagascar; Malaysia;[22] Mauritius (including Rodrigues Island); Mozambique; Myanmar; Papua New Guinea;[23] the Philippines;[5] Seychelles; Singapore;[10] Somalia; Sri Lanka;[24] Taiwan; Tanzania; Thailand;[25] and Vietnam.