Is this algae?

Hello, it's me again. I have noticed this black stuff appearing all over my tank. I was wondering if it's algae. If so, what can I do to get it under control? It grows pretty fast.

I think I am seeing two different things here. On many of the plant leaves there is a black very small fuzzy algae, this is black brush algae (it has two or more forms). I am also seeing what appears to be a black film, reminiscent of cyanobacteria. Is this correct, two things?

Oh, I assumed it was part of the same thing since they're coloured similarly. But what is on the driftwood does look more like film than what's on the plants.

CrystalStars said:

Oh, I assumed it was part of the same thing since they're coloured similarly. But what is on the driftwood does look more like film than what's on the plants.

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I would siphon out as much of the film as you can.

OK, I siphoned as much of it as I can. If it is cyanobacteria, how harmful is it to the fish? And what can I do to reduce its growth? I realized last week that I had the lights on for too long (12 hours). So I reduced it to 10 hours. I haven't been very proactive with removing uneaten food because the corydoras take about 30 minutes or so before they find it. And I want to make sure they're actually eating.

I am suspecting the film is cyanobacteria, but I am only going from the photos and if someone else knows more reliably what this is, all the better. I would certainly get it out quickly, not so much that it is in itself dangerous, but cyano if that is what this is is a sign of poor water quality.

Cyano is caused by organics in the presence of light. It is not directly harmful, and nothing will eat it. The only safe and effective way to get rid of it is to do a water change, siphoning out as much as you can and doing a very deep vacuum into the substrate. Keep the filter clean. Feed less to keep the organics more controlled. Reducing light is hit and miss. This needs light, but blackouts won't do anything long term without dealing with the organics, it will just return. Provided the parameters--being GH, pH and temperature--of tank water and tap water are the same, large multiple water changes will hurt nothing. Loosen this film before, and then vacuum it out. If it is cyano, it will sink to the substrate when you loosen it, easy to suck out.

Food. Do not feed so much that there is excess sinking uneaten. That's the upper fish. Cories need proper sinking foods like pellets, disks, tablets. Bug Bites is the #1 food for cories. They will root these out with their barbels and there will not be any left, unless you really over-feed. A tablet, disk or pellet obviously takes time to get eaten, I have had cories feeding from these for a couple of hours. But don't overfeed.

A trick I used to summon the cories and other fish to eat was to tap gently on the tank frame every time I fed. The fish soon learn what that tap means, and they will be out and scampering about.

In case someone suggests this, do not use antibiotics or any form of algicide or treatment. Never. There is a natural way to deal with this that will not dump toxins in the water.

As always, your replies are much appreciated, Byron.

I think you might be right. I did some research and the film looks like a very dark green version of it. And I can definitely smell... something. I can't describe it. It's like mud or swamp water.

I have been testing the water every other day. Ammonia, nitrite and nitrates are all 0. I'll try to train the fish to come during feeding time because that sounds super handy and kinda cool. Since I haven't added mid level fish, yet. I've been feeding the cories Hikari vibra bites, omega catfish pellets and the occasional Hikari algae wafers. Only a crumb, though. I'll try to pay more attention to removing the food.

I wasn't planning on using antibiotics. It just doesn't seem like a good idea. I'll just try to remove it as much as I can and do water changes.

I'm surprised your Nitrates are 0 with cyanobacteria in the tank...how are you testing? If youre using the liquid test, have a little read of the instructions again to refresh yourself, it'd notoriously a pain in the butt and needs a very vigorous shaking to mix it up

Get a small container of Bug Bites. The mini are OK, but if you have average-sized cories, the next size up is probably better. The mini are good for pygmy cories. This is the food for cories. It is not high in protein which can cause protein excess as white bumps on the cory, and there is no "veggie" food like algae, spirulina, kelp, etc, because cories cannot easily digest these, so better not have them. That eliminates Hikari wafers. Frozen daphnia or frozen shrimp is OK, as treats. Bug Bites should be primary food. Omega One shrimp pellets are very good; crustaceans is #2 in natural food for cories.

I had cyano twice, in the same tank. It took a few weeks each time, but I persevered and it went away. This tank was heavily planted, which was a bit unusual, and the fish load was not that much. But, no matter.

It's a black version of blue green algae (Cyanobacter bacteria). Clean the tank up, increase aeration and water movement, reduce dry food.