What algae eaters can be used?

For my new tank:

  • Zebra Nerite Snails – without the spikes on the shell (NS)
  • Bristlenose Pleco (BN)
  • Siamese Algae Eater (SAE)

Word of caution: I’ve never used the first 2 above in my previous tank. I decided on these for my current tank and I’ve yet to see the outcome. I’ll update here when I know more.

SAEs are generally fast and agile. They survived well in my previous tank and only one got eaten because it nibbled on the arowana’s meal and was too slow to get out of the way. My current arowana is far more aggressive and is constantly on the look out for opportunities to eat the SAEs. So far, 2 confirmed eaten and 4 unaccounted for.

My worry with NS is that they climb into my weir and choke up the drain pipe. I’ll be rigging some wire meshes to prevent that from happening, but you never know… nature has a way of getting into anything. I’ve seen my previous arowana try to eat the tiny snails in my tank. You can see it in the video of my arowana. On one other occasion I’ve seen shell fragments spilling out of its mouth as it chomped on something (probably a ramshorn snail). I am wondering whether it would try eat NS. However, I doubt so as the NS shell is a lot tougher and I don’t think the arowana will swallow it whole. On the other hand, I worry it will swallow one and have it stuck in its stomach.

Update: My snails died before the arowana was introduced. So the jury is out on this.

I am planning to get got the Starlight Bristlenose Pleco (L183). These are beautiful fishes and get to about 6 inches only, not too big. There are many other types of BNs and most get to about 8 to 9 inches. Most BNs are nocturnal by nature, so hopefully that and their size (not very small) will keep them safe from the arowana. The concern here is that they will sometimes scrap on the large plant leaves like those on the Red Tiger Lotus or Amazon Sword Plants and leave them with large unsightly holes. I had one in a smaller planted tank and it did not bother the Red Tiger Lotus in the tank. Other fish keepers report otherwise. It would seem it depends on fish to fish.

Update: My Starlights have so far left my lotus leaves alone. The bad news is they started hiding under the plants and wood and stopped cleaning the glass after getting harassed by my arowana. The sort-of good news is the arowana may (this is a guess) have tried to eat one of them and learnt they are too spiky. That said, all my Starlights are all alive and healthy. Many times I have seen the arowana make a beeline for their location after seeing movement and then turn away at the last moment when it gets close. I can only guess it tried before and got a mouthful of spikes and the victim actually survived. Recently, I have seen them venture a short distance away from their wood and plant havens to graze on the sand, and also large partially cleared spots in the film of algae that I get on glass weekly. I am hoping that as they get bigger they will dare to come out to graze on the open areas, including the glass.

Many commonly used algae eaters are small enough to be eaten and many of them, like Otocinclus, have spiky scales. My first arowana manage to catch an Otocinclus affinis and nearly choked on it. Fortunately it was able to cough it out. It learnt never to eat Otocinclus again, and I learnt the risk of using them in the a predator tank. Shrimps never live long in my previous tank, though I never witness them being eaten by my arowana, I have not been able to find the bodies. My conclusion is that despite their skittishness, shrimps still get caught easily by the arowana. My current arowana is so aggressive that I don’t think I should bother.