Otos Eating Blue Green Algae?

  • #1
I have been having an issue with a lot of blue green algae in my tank. I did not know what this was (still new to aquariums), and thought it was just a normal algae, and was wondering why my Otos were not eating it.

After doing some research as to what this was, I realized it was blue green algae, and have some Ultra Life Blue Green Slime Stain Remover on its way. I also understood why my Oto's have not been eating it.

Back-story, I got 3 Otos almost a month ago. One died the first night (looked sick when I got it), but the other 2 are doing great in my 10G with my Betta. They have definitely gotten longer, and always seem to have full bellies.

Anyways, I looked at my tank this morning (as I do every morning), and I noticed there was a lot less blue green algae on my drift-wood. I'd say there was about half of it gone compared to last night.

I did add some Liquid Fertilizer last night to the tank (Easy Green), so either the dose of fertilizer killed some of it over night, or the Otos are eating it. I wish I had a before and after pic to show.

Is it possible my Otos are eating the Algae, and if so, should I be concerned about their health?
  • #2
I honestly doubt it. There are very few (if any) fish that eat that kinda algae. It's actually not an algae at all, but a type of cyanobacteria that grows like an algae. I could say with 85% certainty that they're probably not eating it.

Do you overfeed at all and how often do you do water changes? I've had the same thing in a planted 20L tank. I had been over feeding and not doing regular water changes on the tank and eventually that stuff was covering all my plants. I could pull it out of the tank in 1 piece it was thick too....I did back to back water changes on that tank and after awhile of continuing regular maintenance it went away on its own.

I'm not saying that you don't keep your tank clean enough (some people do regular water changes and still have this issue) but essentially, some kind of nutrient is out of balance in your tank (theres too much of something, which is allowing the cyanobacteria to grow) and if you eliminate that 'extra something' from the tank (by diluting the water with waterchanges) then it should essentially die off on its own.

If you do end up using the blue/green slime stain remover, be careful not to overdose.
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  • #3
I do weekly water changes, using Prime to condition the water (even though I have a well and no source of chlorine that I know of). I do 50% WC. I have 0 ammonia, 0 Nitrates, and I have about 10ppm Nitrates when I do the WC (before).

I have 2 smaller lights that are run for 4 hours in the morning, and 4 hours in the evening, for a total of 8 hours a day.

The only over feeding I can think of would be that I put 1 algae wafer in a day for the Otos (HikarI brand). I do feed the betta 2 times a day, but I only give him 4-5 pellets per feeding, and I watch him to make sure he eats them all.

I also do fertilizer with the easy green, 1 squirt a week (per instructions, 1 squirt per 10 gallons per week).

Filter is an Aqueon Quietflow HOB 10, with a sponge pre-filter, and I made a larger sponge for the discharge. I did this to calm the water flow for my Betta, but I have also read that too calm of a water will help the Blue Green algae grow. I may have caused the algae with this post-sponge-filter mode.

I have heard that water with too few Nitrates can also cause the Blue Green Algae (and some people say too high Nitrates cause it). I know now that the Blue Green algae is not really an algae, and that is why the Otos were not eating it. Before I did the research, I just thought it was some kind of algae and was confused why the Otos wouldn't eat it.
  • #4
Oh yeah, You did what all aquarists usually do with the blue/green algae. It's very easy to think its a true algae. and indeed you seem to be doing everything correctly.

Maybe it was just a coincidence, but I don't remember what my nitrate readings were (though I could imaging them being high with how I cared for that tank), but I do know that my phosphate was through the roof. When testing for phosphate, the solution in the vial will get thicker, mine was like slimey sludge it was so thick (and dark- indicating that I had high phosphate). So I assumed the high phosphate caused it. and you're also correct with the filter flow. cyanobacteria needs to be able to sit on something before it can multiply nd start growing and the low flow may be contributing.

Considering your cycle is good and you already keep up on your tank pretty well, I would either spot clean the tank (hydrovacing only to get the gunk out, 10% when you do this) or resort to the slime remover. You wouldn't want to deplete your cycle by trying to get rid of all the algae.
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  • #5
Okay, it happened again last night. I took the pictures just before the lights turned off (8:30pm) and took more pics this morning when I got up (6am).

As you can see, the algae is again reduced. This is exactly what happened the night before.

I definitely think my Otos are eating it, I don't see any other explanation why it would disappear overnight, regrow during the day, then disappear at night again.

I did check my Otos this morning, and they seemed fine, fat bellies and swimming normal.


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  • #6
Not familiar with that "algae" but I would say if its mainly on your rock or driftwood I would remove it and run some boiling water over it in a bucket for a few minutes or maybe even boil water and put the pieces in a buckey and pour the water on top and let it sit in there to hopefully kill it. Good luck!!

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