Head-and-Tail Light Tetra

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.

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.

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

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

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

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)