Monster Kok Flowerhorn on show at China International Pet Show

Flowerhorns are aquatic Marmite, in fact, they’re more marginal than that. They’re anchovy pizza. A product of the Malaysian ornamental fish industry, Flowerhorns started off as a hybrid of the Central American Trimac cichlid, “Cichlasoma” trimaculatum.

No one really knows what the other species it was crossed with was but it could have been several, and nowadays they are backcrossed and with numerous other species, line bred, and god knows what else to produce the current varieties.

Flowerhorns are so-called because of the blotch marking on the side of the head hump. The flower is the marking and the hump, the horn. Common Flowerhorn varieties now include Thai silk, Kamfa and King Kamfa and they vary in pattern, body shape and hump size. Short bodied “bonsai” Flowerhorns are also available, though they still get big.

The head hump is known as a nuchal hump science, and many cichlid species develop one naturally including Midas cichlids, Frontosa and Blue dolphin cichlids. In the Flowerhorn community, the lump is known as the Kok. Make sure you spell it correctly and have your safe search on before looking it up on Google.

Being of Amphilophus origin, the Flowerhorn always was capable of developing a large nuchal hump naturally. Especially when in the presence of other Flowerhorns as testosterone is a key driver.

But modern Flowerhorns can have huge nuchal humps, some so large that they cause the fish to be top-heavy, with larger head humps than anything in nature. Autopsies reveal the hump is a hard, gelatinous mass, but just how it has been developed to grow so large in some fish is unknown outside of the commercial Flowerhorn breeders themselves.

Hormones are used in the Far East to develop and exaggerate adult colours in cichlids so they may be used to develop extreme adult humps on young fish. But other factors may be involved and one source suggested Synthol like bogus bodybuilders use to produce huge, unnatural muscle mass.

This Monster Kok Flowerhorn was part of a Flowerhorn exhibition and competition at CIPS in China. It’s certainly the biggest the FKN has seen, as the video shows. What are your thoughts? Cute, hideous, or Megamind?


Aquarium care

Flowerhorns can exceed 12″/30cm in length, so require a six-foot tank when fully grown.  Short body varieties still attain at least 8″ so will require at least a 4x2x2’/120x60x60cm. Like their Central American cichlid ancestors, Flowerhorns require an omnivorous diet, hard water ideally, and can be very aggressive and territorial.

Most are kept as the only fish in the tank, often in bare tanks, although a deep gravel layer will enable digging and sifting, which adds to environmental enrichment for these intelligent fish, when kept alone. Temperatures of 24-28C are fine, and water quality should be good at all times, aided by powerful mechanical and biological filtration.

Colour enhancing foods are often fed to intensify the red colouration, as well as pink-hued colour enhancing lighting. Stores in Asia also offer Kok enhancing foods, although it’s unclear as to if they can cause head hump growth or not, without proper trials.


Jeremy Gay

Author of three fishkeeping books and lifelong fishkeeper. Experience includes editor of Practical Fishkeeping magazine, editor of Pet Product Marketing magazine, multi award- winning livestock manager and aquatic store manager.