What is this?

Where did you get those rocks? If you just grab them from the garden ( not bought from fish store ), it might be that the rocks themselves have chemicals or sediment that might be coming out from them. They may be harmful to fish like copper

Looks like fungus, I had some on driftwood that look similar, but thicker. Haven't seen it come from rocks though. I boiled my driftwood afterwards and it went away, could just be some sort of organic matter?

Let others chime in, but if it's fungus you could probably just boil\scrub the rocks, some plecos would even eat it as food. Don't know about the chemistry of the rocks themselves obviously, you could try putting vinegar on it to see if it foams up.

I wonder if the gavel has old organic matter like food in it? If there is food in the gravel, then it may take a while before your tank is cycled enough to handle it. The fungus may be starting in the gravel and growing around the rocks, maybe because the rocks provide shelter from the current.

Ya. Totally looks like fungus. I have never seen this grow on rock before. Have you tried boiling them? Are the rocks a new addition to the aquarium? What size aquarium do you have? What type of filter do you have?

The only thing i can recommend is daily vaccuum for a week and and see if that helps any. Do this for now until we have some members who can identify this problem for you.

If this is the same type of fungus that seeps out of wood then amano shrimps do an amazing job of keeping this stuff in check.

Do you have wood in your tank? If so it's just biofilm and there's nothing wrong with it. Get some shrimp and they'll eat it all up.

On second thought... maybe you left your light on for too long and it is fungus. My brother-in-law had something similar happen too when he left his lights on for way too long.

Hi all

No driftwood

Removed all rocks. Boiled scrubbed and lightly bleach them. Then rinsed many times and soaked overnight in fresh water.
What comes off in water resembles egg white when you make eggs Benny, and I can pick up the larger strands with my fingers!


It IS weird it's only in these rocks. Rocks came with full scaped tank. Seller buys used tanks and accessories and reorganizes into beautiful tanks. Sets them up with water no livestock then sells them for a profit

At least that's what he said. 46 gallon bow front with roofing 69 filter. I have my fluval 306 with inline heater ready to install but no way was I doing anything else till I got this slime under control.

Also 5 neons perfect health since Sunday in tank with awful rocks. Lightly fed daily.

Keep an eye out on your fish. If they start to act funny then there is something wrong with the water. If ur neon tetra are healthy I wouldn't worry to much. Neon tetra will let you know right away if there's something wrong. I highly recommend getting amano shrimp though. Get them as big as you can get. Theyll eat the hell out of fungus and on top of that theyll keep your tank very clean and they are great to watch.

Keep us posted!

It definitely looks like either a fungus or a bacterial growth. I have had something similar with wood and guppies ate it all over night many years ago. Given it is a new tank, there is a good chance that it will go away once things balance out. It is definitely finding something it likes. My guess is bacterial bloom, but I do not know why is relating to something inorganic....but I am not a microbiologist

I am adding to this post ....there is an earlier thread on something like this.....I found a bcaquaria based thread when I googled white fluffy growth in tank..

Yeah we tend to see it on new wood that goes into the tank for the first time. Rare to see it on rocks. But nothing says bacteria can't live on rocks.

Sent from my Nexus 6 using Tapatalk