Hemigrammus erythrozonus (glowlight tetra)

Hemigrammus erythrozonus, also known as glowlight tetra are small tropical fish that is found in the wild in Essequibo River, Guyana, South America. It is silver in colour and a bright iridescent orange to red stripe extends from the snout to the base of its tail. The front part of the dorsal fins are the same color as the stripe. Other fins are silver to transparent. Glowlight tetras are peaceful and shoaling fish. It is slightly larger than the neon tetra, and its peaceful disposition makes it an ideal, and popular community tank fish. They should be kept with similar sized and non-aggressive species.
They are a medium size tetra growing to up to 4 to 5 cm (1.6 to 2 inches), notably larger than both neon tetras and cardinal tetras. They have a life span of 2 to 4 years when kept in good conditions.
Glowlights are omnivorous, they eat small live, frozen and dry foods. The feeding of vegetable matter is suggested to vary the diet of the glowlight tetra.
Glo lights, glo-light tetras, and glolights are alternative names. H. gracilus is old scientific name. Red-line rasbora ( Rasbora pauciperforata) of Malaysia and Indonesia are different species with similar coloring. Glowlight tetras are readily available and are usually very inexpensive. There is a golden glowlight tetra and albino glowlight variety being offered for sale too.

Water conditions
They are best seen in the aquarium if kept in subdued lighting with dark substrate - background. They can be kept in tanks 20L or larger, 50L being ideal. The water should be soft to slightly hard. d°GH of 6° to 15°. Use a slightly acidic pH of 6.8 in the range 6.0 - 7.5. The prefer a temperature of 25 °C in the range of 22° - 28° °C (72° - 82 °F). The hardiness of this tetra variety allows it to easily adapt to harder water, although soft water is essential if you intend to breed this variety.

Shoaling
Like all small tetras, glowlights (Hemigrammus erythrozonus) are happiest, most active, and most aesthetically pleasing when in a shoal. A minimum aquarium length of 60 cm will make them more comfortable when swimming. Glowlights prefer a well planted tank for hiding, but with some open water for free swimming. They should be a group of at least four with eight or more to make them feel secure. They tend to swim in smaller groups when a potential predator is present and swim freely when comfortable. They are often bought by aquarium owners to play a 'second fiddle' role to the neon tetra. Although they generally shoal separately from neons and cardinal tetras, they will often shoal alongside the latter, making an arresting visual spectacle. Listed as medium-level swimmers, glowlight tetras tend to stay about an 3 cm off the bottom except when fed when they come up to the top.

Gender
Like most tetras, females are larger and more fat bodied than the more slender male. It may be hard to tell male from female until the fish are fully mature and females fill with eggs.

Breeding
Glowlight tetras breed similarly as most egg-scattering small fish. They have been bred in captivity as moderate level of difficulty. A small 40L all glass tank with soft water hardness up to 8°dGH is needed for breeding. Carbonate hardness should not be higher that 1°dCH. Water temperature should be kept between 26 and 28 °C. Adding peat to the tank or filter will soften water and make it slightly acidic. The tank should have dim or no lighting. They spawn over fine-leaved plants. Java moss, Fontinalis and Vesicularia dubyana are suggested. 1 cm glass beads or a spawning grate may help at the bottom to protect eggs from being eaten by adults.
Feeding the pair with live foods for a few weeks can help induce spawning. The pair should be kept separately and put in the breeding tank in the afternoon hours only when the female seems ready. At the end of each spawning act, both fish turn upside down and the female ejects the eggs in this position. Usually 120-150 eggs are dropped in plants and on the bottom. Parents should be removed after spawning. If no spawning occurs in a few days, remove them and reclean the tank and try the process over again.
The eggs are light sensitive, so the breeding tank should be as dark as possible. Some believe the light contributes greatly to the eggs fungusing, though fungusing has more to do with cleanness of tank and water conditions. The fry will hatch in 20 to 25 hours. They should look like small slivers of glass. Fry can be feed with, infusoria, paramecium culture, crushed flakes and rotifers. By the 4th day should be introduced very small portion of newly hatched brine shrimp. Young consume relatively large pieces of live food such as nauplii of brine shrimp. Later microworms can be added to the diet. Live food has the advantage of less pollution in the water, in case not consumed immediately.
Bottom sediment should always be removed and regular water changes done during the rearing period in order to avoid an accumulation of ammonium and nitrates which can be toxic to the fry. Although large quantities of fry will incubate in waters of low hardness, most of the fry may soon contract non-infectious, constitutional dropsy, and die within a short time. Those who survive will grow well. By the 12th day, they will show signs of a silver coloring. At three weeks of age, the fry will start showing their characteristic orange line and will be a size of about 1 cm. By two months they will be about 2 cm.

Tankmates
The Glowlight tetra can be kept with fish with long fins such as Betta splendens.They are one of the more peaceful tetras.It is not recommended they be kept with anything larger than a Blue gourami, but successful attempts have been recorded. They can be housed with fairly sizeable herbivorous fish like pacus or plecostomus.

http://en.wikipedia.org/wiki/Hemigrammus_erythrozonus