[Ebook] The New Guide to Aquarium Fish – Koi Carp

Some of you may be tempted to keep Cyprinus carpio (Koi Carp) in an aquarium and we would like to advise against this. Koi are potentially large fishes best housed in large purpose-built ponds with powerful filtration systems.

Bitterling

The various subspecies of Rhodeus sericeus (bitterling) are available during the summer months and are ideal for the aquarium as they are easy to keep, and feed on just about any small foods. They also have an unusual method of breeding, and need a swan mussel to spawn in. This alone makes them worth the effort.

When ready to breed, males are almost olive green along the top of the head and the back, with iridescent shades of blue, pink, and violet along the flanks. Females are yellower and show an ovipositor. Breeding is stimulated by a rise in water temperature to about 22°C (72°F).

Use a tank with a sand substrate and thickets of plants, and several live Swan Mussels (Anodonta sp.). The male keeps nudging the mussel with his mouth to stimulate it to remain open, while the female places her ovipositor in the mussel’s outlet valve and deposits her eggs. The male follows, swiftly shedding his milt over the mussel and thereby fertilizing the eggs. Some 30 days later the fry leave the mussel and have to be raised on very fine live foods.

Recent importations

Over the last couple of years some unusual fishes have been arriving from the Far East. One of these, Myxocyprinus asiaticus, is a large cyprinid (family Catostomidae) from China. Sold under the name Chinese sailfin, small specimens are highly coloured and very attractive; they are marbled with brown on a lighter cream or beige background, and the high dorsal fin makes them most appealing. The problem is that these small, endearing, 15-20 cm (6-8 in) fishes grow to more than 60 cm (24 in), so unless you can cope with this, leave them to public aquaria. This North American fish, Notropis lutrensis (shiner), requires cooler temperatures in winter than in summer.