Head-and-Tail Light Tetra
Hemigrammus ocellifer
Also known as: Beacon fish, Beacon tetra
This little tetra does a neat trick in the light-there's a shiny "headlight" spot near the gills and a glowing "taillight" at the base of the tail, so the whole school kind of sparkles as they turn. They're super chill in a group, and they look way better the bigger the shoal is and the more plants you give them to cruise through.
The Head-and-Tail Light Tetra features a striking iridescent body with a prominent dark spot at the base of the tail and a delicate bluish sheen.
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Quick Facts
Size
2 inches
Temperament
Peaceful
Difficulty
Beginner
Min Tank Size
15 gallons
Lifespan
3-5 years
Origin
South America
Diet
Omnivore - small flakes/micro pellets, frozen foods like daphnia/brine shrimp, and the occasional live food
Care Notes
- Keep them in a group of at least 8-10 - they get bolder, color up better, and stop acting twitchy when they have a real shoal.
- A 20-gallon long works great for a group; add plants (real or fake), some driftwood, and a darker substrate if you want that head-and-tail light to pop.
- They are pretty forgiving, but they look best around 74-80F with a steady pH in the 6.5-7.5 range; avoid big swings and do regular weekly water changes.
- Feed small stuff they can finish fast: flakes, micro pellets, and frozen/live brine shrimp or daphnia a few times a week - go light so you do not end up with a nitrate factory.
- Good tankmates are other peaceful community fish like corys, small rasboras, and calm gouramis; skip fin-nippers and big mouthy fish that see them as snacks.
- They can get nippy if the group is too small or the tank is cramped, so if you see chasing, add more of their own kind and give them more plant cover.
- If you want to breed them, set up a separate tank with a mesh or marbles on the bottom because they will eat the eggs; a clump of fine plants and slightly warmer water helps get them going.
Compatibility
Good Tankmates
- Other small, chill schooling tetras (ember tetra, neon tetra, black neon) - they all do the same vibe, just keep everyone in decent group sizes so the head-and-tail lights dont get skittish
- Harlequin rasboras and other peaceful rasboras - similar speed and attitude, and they look great sharing the midwater
- Corydoras catfish - perfect bottom crew, totally ignore the tetras, and the tetras seem calmer when corys are doing their thing
- Small peaceful plecos like bristlenose (Ancistrus) or otocinclus - good algae help, no drama, just make sure theres real food for otos
- Honey gourami (or other gentle gouramis) - works well if the tank isnt cramped, gourami stays chill and the tetras keep to the middle
- Dwarf cichlids like apistogramma or a calm pair of rams - usually fine because the tetras are quick and not finny, just give the cichlids caves so they dont get crabby at spawning time
Avoid
- Tiger barbs - classic bad mix, they get nippy and the head-and-tail lights spend the whole time dodging and hiding
- Fin-nippers in general like serpae tetras (and similar rowdy tetras) - they can turn the tank into nonstop chasing
- Big hungry stuff like angelfish or larger cichlids - once the angel is grown, those little tetras start looking like snacks
- Super slow fancy-finned fish like longfin bettas or fancy guppies - even peaceful tetras can get tempted to peck at flowing fins, especially if the tetra group is too small
Where they come from
Head-and-Tail Light Tetras (Hemigrammus ocellifer) come from northern South America - think slow-moving creeks and backwaters with plants, roots, leaf litter, and tea-colored water. They are one of those little tetras that look kind of plain in a bare shop tank, then you get them home and the gold sheen and those "lights" at the head and tail start popping.
Setting up their tank
You can keep these in a smaller community tank, but they look and act way better with a bit of room to school. I have had the best luck keeping them relaxed and colorful in a planted setup with open swimming space in the middle.
- Tank size: 15-20 gallons is a nice starting point for a proper group (bigger is always easier to keep stable).
- Group size: 8-12 minimum. In smaller numbers they get shy and the fin-nipping tendency can show up.
- Filter: any gentle filter works. They do fine with sponge filters or a hang-on-back with the flow turned down.
- Decor: plants (real or fake), some wood or rock, and a darker substrate makes the "light" spots stand out.
- Lighting: moderate. Too bright and bare can make them skittish. Floating plants help a lot.
If you want them to look their best, give them a dark background and a few shaded areas. The head and tail spots read way clearer against darker surroundings.
Water-wise, they are pretty forgiving for a tetra. Aim for typical community parameters: mid-70s F (around 74-78F is a comfy range), stable pH somewhere in the 6.5-7.5 neighborhood, and keep ammonia/nitrite at zero like always. What they really hate is a tank that swings around or gets neglected.
They are small fish with small stomachs, so a dirty tank hits them faster than you might expect. Regular water changes beat "fixing" problems later.
What to feed them
They are easy eaters. Mine take flakes right away, but they color up and fill out better when you mix in a few smaller foods. Think "tiny bites, variety, and not too much at once."
- Staple: good quality micro pellets or crushed flake
- Treats that make a difference: frozen baby brine shrimp, daphnia, cyclops
- If you have it: live baby brine shrimp is like a cheat code for getting them active and showing color
- Feeding schedule: 1-2 small feedings a day, only what they clear in a minute or two
If food is sinking straight past them, try a finer pellet or crumble flake between your fingers. They are midwater pickers and do better when the food hangs in the water column.
How they behave and who they get along with
These are classic peaceful schooling tetras. They spend most of the day cruising the middle of the tank, and the group will tighten up and loosen naturally depending on light, flow, and how secure they feel.
In my tanks they are friendly, but like a lot of small tetras, they can get a little nippy if you keep them in too small a group or cram them into a tiny tank. Give them numbers and space and that behavior usually disappears.
- Great tankmates: other small peaceful tetras, rasboras, corydoras, otocinclus, small plecos, peaceful dwarf cichlids, most shrimp (adult shrimp usually fine, babies may get hunted)
- Use caution with: long-finned fish like bettas, fancy guppies, and slow-moving angels (some groups are perfectly fine, some get curious and start testing fins)
- Avoid: big aggressive fish, anything that sees a 1.5 inch tetra as a snack
If you see chasing or nipping, the first fixes are usually: add a few more tetras to the school, add plants for line-of-sight breaks, and check that you are not over-lighting a bare tank.
Breeding tips
They will occasionally scatter eggs in a mature planted tank, but raising fry in a community setup is pretty rare because the adults (and basically everyone else) will eat the eggs. If you actually want babies, you will have a lot more luck using a separate breeding tank.
- Setup: 5-10 gallons, sponge filter, heater, dim light
- Spawning medium: clumps of java moss, spawning mop, or a mesh/egg crate so eggs fall out of reach
- Conditioning: feed frozen/live foods for a week or two
- After spawning: pull the adults the same day (they do not guard eggs)
- First foods: infusoria/liquid fry food, then baby brine shrimp as soon as the fry can take it
If you do not want a whole extra tank, the low-effort method is heavy java moss plus lots of microfoods in the main tank. You might get the occasional survivor, especially if the tank is packed with plants.
Common problems to watch for
Most issues I see with Head-and-Tail Lights are the same "new tetra" problems: stress from shipping, getting added to an uncycled tank, or being kept in too small a group. Fix the environment and they usually bounce back fast.
- Ich after adding new fish: quarantine new arrivals if you can, and do not buy fish with clamped fins or white specks in the store
- Fin nipping: almost always tied to small group size, cramped space, or not enough cover
- Faded color and hiding: bright bare tanks, boisterous tankmates, or unstable water (they act nervous when things swing)
- Wasting away despite eating: internal parasites can happen in tetras - watch for stringy white poop and a pinched belly
- Sudden losses: check ammonia/nitrite first, then temperature swings, then oxygenation (small fish go downhill fast in bad water)
Do not chase numbers like "perfect pH." With this species, steady and clean beats fiddling. If your tap water is reasonable, spend your energy on regular maintenance and a calm tank layout.
Similar Species
Other freshwater peaceful species you might be interested in.
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