Fish With Big Head: 8 Species With Huge or Bulging Heads

The fish most often meant by 'fish with a big head' is the bighead carp, Hypophthalmichthys nobilis, which Wikipedia describes as having a large, scaleless head, a large mouth and eyes set very low on the head. If you mean a fish with a bulging forehead, the usual answers are the humphead wrasse, the Asian sheepshead wrasse, the green humphead parrotfish, the flowerhorn cichlid, the oranda goldfish or a bull mahi-mahi. The first group has a head that is large compared with the body; the second grows a lump of tissue on top of an ordinary head.

• Bighead carp (Hypophthalmichthys nobilis): usually 60 cm, up to 146 cm and 40 kg; native to large rivers of eastern Asia from southern China to the Amur (Wikipedia)
• Humphead wrasse (Crassilabrus undulatus in Wikipedia's current naming): males up to 229 cm and 191 kg, with a hump on the forehead of larger adults, thick lips and two black lines behind the eye. Endangered on the IUCN Red List and listed in CITES Appendix II (Wikipedia)
• Asian sheepshead wrasse (Bodianus reticulatus): up to 100 cm and 14.7 kg; males develop a bulbous forehead with age, and the fish can live 40 to 50 years (Wikipedia). Its sex change was filmed for Blue Planet II in 2017
• Green humphead parrotfish (Bolbometopon muricatum): the largest parrotfish, up to 1.3 m and 46 kg; listed as Vulnerable (Wikipedia). See our parrotfish page
• California sheephead (Bodianus pulcher): a wrasse of the Pacific coast from Monterey Bay to the Gulf of California; adult males grow fleshy bumps on the forehead (Wikipedia)
• Flowerhorn cichlid: a man-made hybrid first bred in Malaysia in 1993, known for its nuchal hump or kok (Wikipedia)
• Oranda goldfish: a fancy goldfish with a bubble-like hood that may cover the whole face except the mouth; 20 to 31 cm long (Wikipedia)
• Mahi-mahi (Coryphaena hippurus): mature males have a tall forehead that often rises well above the body, while females have a rounded head (Wikipedia). See our dorado fish page

A forehead hump is often a sign of sex and status, which makes it a useful ID clue:

• Wrasses that change sex: Asian sheepshead wrasse and California sheephead are born female, and the forehead bump develops after the change to male (Wikipedia). The humphead wrasse also changes from female to male, and the hump appears on larger adults (Wikipedia). A big hump on these species usually means you are looking at a mature male
• Ramming: male green humphead parrotfish charge and collide head-on hard enough to make loud jarring sounds; Wikipedia compares the humps to bighorn sheep horns
• Mahi-mahi: the tall forehead marks a mature male, and females keep a rounded head (Wikipedia)
• Selective breeding: the oranda's hood and the flowerhorn's kok were bred for by fish keepers. The oranda's head growth takes one to two years to develop in young fish (Wikipedia)

None of the top-ranking pages we read explain this, but for identification it matters: in a sheephead or humphead photo, a hump tells you both the species group and the sex.

Look for the very low-set eyes, the large scaleless head and mottled silver-grey colouring (Wikipedia). Its close relative, the silver carp, is the one that leaps out of the water when boats pass; Wikipedia notes that bighead carp do not jump when startled by boats.

In the United States bighead carp escaped into the Mississippi River basin, are now firmly established and are considered a highly destructive invasive species; a national control plan was finalised in 2007 (Wikipedia). Wikipedia notes that their filter feeding makes them a challenge for sport fishing. If you catch one, do not move it alive to other water, and check your state wildlife agency's rules on invasive carp.

As food, bighead carp are popular in Asia and less so in North America; the flesh is white and firm, with intramuscular bones (Wikipedia). For fish from your local water, check the consumption advisory for that river or lake first.

• Flowerhorn: importation is banned in Australia, and discarded flowerhorns have become an invasive pest in Singapore and Malaysia, where they compete with and eat native fish (Wikipedia). Never release one
• Oranda: the wen can grow over the eyes and leave the fish with limited sight or blind, is easily injured by rough decorations and is prone to bacterial infection (Wikipedia). Wikipedia suggests keeping heavily hooded fish with other poor-sighted goldfish so they are not out-competed for food

Photograph the whole fish side-on, then the head from the side and from slightly above so the forehead profile shows. Note where the eyes sit (low on the bighead carp), whether the lips are thick (humphead wrasse) and whether the hump is smooth tissue or a bony ridge. FishLens will suggest the likely species from the photo. For look-alikes, see our common fish look-alikes guide.

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Every number names the organisation it comes from; where sources disagree we say so instead of picking one silently. Prices and counts are given with the date we checked them. If you find an error, tell us and we will correct it.