|Sexual Dimorphism||Mature females fuller bodied. Mature males show breeding tubercles on gill plates & pectoral fins.|
|Maximum Size||20cm (7.9")|
|Temperature||Temperate: 18-22 deg C (65-72 deg F)|
|Water Parameters||Neutral to alkaline conditions preferred. pH: 7.0-8.0, dH: up to 25 degrees.|
|Compatibility||Fancy goldfish community.|
|Lighting||No special requirements|
The Ryukin is a selectively bred high-backed, double-tailed strain of the common Goldfish. Fancy goldfish have long been popular aquarium pets, and are often the aquarists first venture into keeping aquarium fish. Given appropriate housing and care, these beautiful fish can attain quite a size and live for 15-20 years. The aquarium should be spacious with a large area for oxygen exchange; the length and width of the tank are much more important than the height in this respect. Fancy goldfish grow quickly so it is best to provide them with the largest aquarium that you can from the outset. Not only will this help to avoid stunting (and the associated health problems this can bring) but it will also provide a much safer, more stable environment for them. The larger the volume of water, the more stable it will be in terms of water chemistry and temperature. Fancy goldfish are notoriously messy fish; they are voracious eaters and continually stir up the substrate in their ongoing search for food - and such considerable amounts of waste can lead to water quality issues in smaller aquaria if not monitored very closely. The larger the aquarium, the better. Efficient filtration is essential, and regular partial water changes are advised in order to keep nitrate to a minimum. The water should be well-oxygenated (of particular importance during warmer spells of weather) and this is easily achieved by the use of spray-bar returns from filters, air pumps, small powerheads with flow diverter angled towards the water's surface etc, and may be aided further by the incorporation of oxygenating aquatic plants, which the fish will also enjoy nibbling at. Various species of coolwater tolerant plants can be added to the aquarium, but these will likely require periodic replacement due to them being uprooted/eaten - something most goldfish keepers accept and allow their fish to take pleasure in. The substrate can consist of rounded gravel or sand, and decor can include smooth rocks and ornaments with no sharp edges. Ryukin are sociable creatures and should be kept in groups, either with their own kind or with other varieties of fancy goldfish. It is best, however, to avoid keeping the standard 'single-tailed' common goldfish alongside the fancy varieties, as the common goldfish is a faster swimmer and may outcompete the fancies at feeding time. Several colour varieties of Ryukin are available, including red, red and white, and calico.
Flake, pellets, sticks, along with various frozen foods such as bloodworm, white mosquito larvae, vitamin-enriched brineshrimp etc, and some vegetable matter.
Well-conditioned fancy goldfish will spawn in the home aquarium. Female fish will be noticeably rounder bellied when full of eggs, and the male fish will develop tubercles (tiny raised bumps) on the gill plates and pectoral fins. A large, slightly cooler water change is often enough to trigger ready pairs into spawning. As the temperature slowly rises back up to its usual level, the male will pursue the female around the aquarium, but generally in a non-aggressive manner. This courtship ritual may last more than a day before spawning commences, and the colours of the fish often intensify at this time. The male fish will nudge the female into the fine-leaved plants (or spawning mops), where she will then scatter eggs which the male simultaneously fertilises. Spawning can last for a number of hours, and several thousand adhesive eggs may be scattered over the plants/spawning mop. The adults will be hungry and will start to devour as many eggs as they can find, so are best moved to another aquarium. The eggs take 4-5 days to hatch, depending on water temperature. Young fancy goldfish are often brown in colour (like their ancestors) and it can take up to a year before full colouration becomes apparent.