Black spots on Anubias nana Coin.

I have a relatively new 240l tank with 12 neon Tetra, 6 Gold laser Corey and 6 Clown Loaches. Everyone is getting along well and all of the other plants are doing well. So good that I've taken cuttings of some and planted them.
The only one not looking good is the Anubias which has black spots on it. Is this a fungus or uneaten food?

seems to be diatoms or black beard algae.
either way, use 2 fingers to try and rub the algae off. make sure to keep leaf in place while rubbing or it may rip.
it's not a big problem because its easy to remove and doesnt cover the whole leaf

Use glutaraldehyde or hydro proxide to dip. Or if you already attached it to hardscape then use turkey baster or syringe to inject direct on leafs. Small quantity will not disturb fish unless you have shrimps in your tank. Good luck.

There is no point in any form of treatment as the algae will continue to occur. You need to resolve the cause, not bandaid it with potentially dangerous chemicals. If it easily comes off with your fingers, it is diatoms. But if it does not come off easily, it is black brush algae. I suspect the latter, because it is very common on Anubias (and Java Fern) when these are grown in direct light. They are low light plants, and do best with some floaters above them. Then this algae if bba will not increase.

Thanks. Looks like it is diatoms as it comes off very easily when rubbed between my fingers.

Off now to Google diatoms.

Gaagaad said:

Thanks. Looks like it is diatoms as it comes off very easily when rubbed between my fingers.

Off now to Google diatoms.

Click to expand...

it will most likely go away in a while. since your tank is "relatively new" there are still a lot of silicates in the substrate. when those are all used up, diatoms will be rare. at least that is my observation.