大鳍鱊 · Giant Chinese Bitterling

Overview

The bitterling Acheilognathus macropterus requires substantial accommodation and is an occasional aquarium import. Its dependence on live mussels for reproduction makes it a specialist breeding project, best approached by experienced keepers with adequate facilities.

Distribution & habitat

It occurs naturally in China, Korea, northern Vietnam and southeastern Russia. Japanese populations are introduced and regarded as invasive. Vegetated river margins with little current are typical settings, but the fish also thrives in sizeable standing waters, including reservoirs.

Aquarium setup

Use a spacious aquarium with a gentle river-style layout. Sand and gravel can be mixed with rounded stones and a few larger rocks. Wood and hardy plants anchored to the decorations provide further structure.

Diet & feeding

Both animal and plant material are eaten in nature: insects and larvae accompany algae and other vegetation. Most aquarium foods are readily accepted. A dependable dry food can supply the everyday base, with regular small live or frozen foods adding variety and supporting condition.

Behaviour & compatibility

Outside reproduction it is generally nonaggressive. Nevertheless, a large adult may consume a much smaller fish. Choose peaceful companions of comparable size with matching environmental needs. Males become defensive toward rivals during spawning.

Sexual dimorphism

Longer dorsal and anal rays distinguish males. Reproductive males develop stronger colors, a pinkish metallic sheen, a darker belly, snout tubercles and white markings on the anal fin. Females approaching spawning develop a conspicuous egg-laying tube, and the anal fin takes on yellow coloration.

Breeding

Eggs are placed inside a living mussel rather than scattered around the aquarium. The female inserts her ovipositor through its outgoing siphon; sperm released at the incoming siphon reaches the eggs within the gills. Young remain in this protected site through early development before emerging as swimming fry. A female may use several mussels, while a single host can receive eggs from multiple females.

The natural host used by this species has not been established, so successful breeding cannot be assumed with an arbitrary mussel. An introduced Japanese population does use a local host, but that observation alone does not resolve how flexible host selection is.

Notes

The wide distribution may conceal several closely allied species. Identification and population boundaries therefore deserve caution. Maintaining suitable mussel habitat is also relevant to the fish's reproductive survival.