- Scientific Name: Hemigrammus ocellifer
- Synonym: Hemibrycon ocellifer, Hemigrammus ocellifer falsus, Holopristis ocellifer, Tetragonopterus ocellifer
- Common Name: Beacon Fish, Beacon Tetra, Head and Tail Light Tetra
- Family: Characidae
- Origin: Argentina, Brazil, French Guiana, Guyana, Peru, and Suriname
- Adult Size: 2 inches (5 cm)
- Social: Peaceful schooling fish
- Lifespan: 5 years
- Tank Level: Mid dweller
- Minimum Tank Size: 15 gallons
- Diet: Omnivore, eats all foods
- Care: Easy
- pH: 6.0-8.0
- Hardness: 5-19 dGH
- Temperature: 72-79 F (22-26 C)
Hemigrammus ocellifer originates from South America, where it can be found in numerous locations along the Amazon and Orinoco river basin, as well as along the coast of Guyana. Favoring slow-moving rivers and streams, it can be found in Argentina, Brazil, French Guiana, Guyana, Peru, and Suriname. However, wild caught specimens are rarely sold in the trade, as most are now captive bred for commercial sale.
The scientific name comes from the Greek Hemmigrammus meaning "half line", which refers to an incomplete lateral line, and ocellifer which means "eye bearing", a reference to the reflective spots or "eyes" on the head and tail of the fish. First described as Tetragonopterus ocellifer, this species was later moved to the Hemigrammus genus.
However, the classification is still uncertain, as experts agree the genus is not monophyletic, and further revisions are likely.
Head and Tail Light Tetras, Hemigrammus ocellifer, are named for two coppery colored reflective spots that resemble tail lights. One is located at the base of the tail and the other is near the head, next to the gill cover.
These reflective patches are coupled with a black spot. Hemigrammus ocellifer falsus, has been named as a possible subspecies. It is more slender and has the “tail light” spot, but lacks the spot behind the gill cover, and is currently not recognized as a separate species.
The body is iridescent silver in color and like many other Tetras is oval in shape. Seen from above, the body is compressed, with the males being thinner than their female counterparts. The upper rim of the eye is edged in brilliant red, similar to the Red Eye Tetra. The fins are translucent, and on some specimens, a fine black line runs from mid-body to the spot on the tail fin. Adults reach a length of approximately two inches (5 cm).
Head and Tail Light Tetras do best in schools of a half dozen or more and can be kept with other peaceful fish, particularly other members of the Tetra family. Barbs, Danios, Rasboras and other small to medium sized peaceful fish are also good companions. Small Loaches and Catfish, Dwarf Cichlids and smaller Gouramis are also suitable.
Avoid fish that are large enough to eat them. Some owners report that their Head and Tail Light Tetras will nip the fins of slow-moving long-finned species such as Angelfish and Bettas. However, I have not had such experiences myself.
Head and Tail Light Tetras are generally undemanding in habitat. They should be provided with planted areas, either real or artificial. Floating or tall plants that reach the top of the tank to provide shade are particularly desirable, as this fish prefers subdued lighting. A darker substrate will add to the subdued décor and set off the coloration of the Head and Tail Light Tetra. Open swimming space in the middle will complete the ideal tank arrangement.
Omnivorous in nature, the Head and Tail Light Tetra will eat most foods, but will not nibble on the live plants. Provide a good variety of flake foods along with freeze-dried or frozen live foods, such as brine shrimp, bloodworms, and small insects. They will eat fine pelleted food as well. Live foods should be used when conditioning before breeding.
Females are rounder and plumper than the male, particularly when viewed from above. The swim bladder in the male is pointed and more visible than the rounded swim bladder in the female. Because this fish is translucent, it is possible to view the swim bladder by using a strong light.
An egg layer, Hemigrammus ocellifer is relatively easy to breed. The tank should be fitted with plenty of plants for the breeder pair to lay their eggs on. Lighting should be dim. Water in the aquarium should be soft, temperature 80 F (26 C), and pH slightly acidic in the range of 6.0 – 6.5.
Condition the breeder pair with live foods for a week or two. Bloodworms and brine shrimp are good choices, and frozen may be used if live is not available. As the spawning time approaches, the belly of female will swell noticeably with eggs. Spawning typically occurs in the morning, with up to a thousand eggs being laid over the course of the day.
Once the eggs are laid, remove the parents promptly, as they will consume the eggs and young fry. The eggs will hatch in 24 hours, and the fry become free-swimming within another two days. During this time, make sure the lighting is very subdued. If the room is brightly lit, it is wise to drape the tank to reduce the light. Feed the fry commercially prepared fry food, egg yolk, or paramecium. Within a few days freshly hatched brine shrimp can also be fed to the fry.