Golden Tetra

About

The golden tetra (Hemigrammus rodwayi) has one of the more surprising origin stories in the hobby. Wild fish from Guyana, Suriname, French Guiana, and parts of the Amazon basin can develop a brilliant metallic gold sheen across their bodies, but that color isn't genetic. It's a response to a skin-dwelling trematode parasite that triggers guanine deposits in the tissue. When these golden fish were first collected, they were described as an entirely separate species, Hemigrammus armstrongi, before researchers realized what was actually going on. Captive-bred specimens, never exposed to the parasite, revert to the species' baseline appearance: a modest silvery-grey fish with a little color in the fins. Most fish sold under the golden tetra label look nothing like the name suggests, which catches new buyers off guard. Occasionally, infected wild-caught individuals appear in the trade, and the difference is dramatic. Regardless of coloration, this is a peaceful, active schooling fish that should always be kept in groups of at least six, and ideally ten or more. It pairs naturally with other small South American species. Pencilfish, Corydoras, Apistogramma, and related tetras all make good company. It won't hold its own against boisterous or aggressive tankmates, so a calm, well-matched community suits it best. Breeding is achievable in a separate setup with soft, acidic water.