You have algae on your glass. You have algae on your plants.
You go to the shop and ask for an “Algae Eater.”
The uncle points to a long, grey fish sucking on the glass. “Chinese Algae Eater. RM3. Very hardworking.”
Do not buy it.
That fish will grow to 6 inches, stop eating algae, and eventually suck the slime coat off your other fish.
If you want a true professional—a fish that eats algae non-stop, stays tiny, and never hurts a fly—you need the Otocinclus Catfish (Otocinclus macrospilus).
1. The “Dwarf” Suckerfish
Unlike the Pleco (which grows to 1 foot) or the Chinese Algae Eater (6 inches), the Oto stays tiny.
- Size: Max 1.5 to 2 inches.
- Safety: They are the only algae eater that is 100% safe for planted tanks and shrimp tanks. Their mouths are so soft they cannot damage delicate plant leaves.
2. The “Starvation” Warning (Crucial)
Otos have a reputation for being “fragile” or dying in the first week.
It isn’t because they are sick. It is because they are starving.
Otos are wild-caught. By the time they arrive at the LFS in Malaysia, they haven’t eaten properly in weeks. Their stomachs rely on special bacteria to digest algae.
- The Check: When you buy them, look at their bellies. A healthy Oto has a round, pearl-like belly. A dying Oto has a sunken, flat belly.
- The Rule: Do not put them in a brand new, sparkling clean tank. They need algae and biofilm to survive. Only add them to a tank that has been running for 2-3 months.
3. They Are Social!
This is the biggest surprise for most owners. Otos are schooling catfish.
If you buy just one, it will hide.
If you buy 4 to 6, they will gain confidence. They will play tag, chasing each other up and down the glass like little puppies.
4. How to Feed Them (The Cucumber Trick)
If your tank is too clean, your Otos will run out of food. You must supplement their diet.
They rarely eat flake food. They need veggies.
- The Recipe: Take a slice of Japanese Cucumber or Zucchini. Boil it for 2 minutes to make it soft (blanching). Stick it on a fork and drop it in the tank.
- The Result: Within an hour, your Otos will swarm it. Remove the leftovers after 24 hours so it doesn’t rot.
5. Why They Are Better Than Plecos
- Plecos: Eat algae when young, become lazy when old. Poop constantly.
- Otos: Eat algae 24/7 until the day they die. produce very little waste.
The Bottom Line
The Otocinclus is the unsung hero of the planted aquarium. They work harder than any machine filter.
If you have a 2-foot tank with real plants, skip the Pleco. Get a “Gang of 6” Otos. Just remember to feed them their veggies!
