I think I have cyanobacteria in my tank

[Big C]

Hi all,
I've been working to hard ad traveling a lot in the last few months, yet always managed to keep up with my tanks cleaning and maintenance. Even in the last two weeks, when I was away for the whole time, I trained my hubby to do a pwc for me.

For a few months now I've noticed some bright green slimy stuff on the glass lid of my large tank. It always grows in the same two spots, the two back corners. All the equipment is in there: input and output of the two filters, the heaters, and the air bubbles. And the light hood is on top. The slime has a powerful chemical smell, almost like pesticide. I have not seen any of it under water, although sometimes it seems to infect some of the plants that grow above the surface which a prune every week.

I have lost 4 fish in the last 5-6 weeks. A dwarf gourami, a female GBR, a serpae, and a male GBR. The female GBR, was not doing very well from the beginning, the gourami just started hidding from the gold gourami and then I found it dead one day. The other two died with their bodies in a curl (like a C shape). The male GBR who was nice and healthy when I left died while I was away, and I found his body yesterday when I changed the water in the same C shape.

I also lost a barb from the small tank in the same way. There is no slimy stuff in the barb tank but I use the same phyton to clean the tanks.

All the other fish look very healthy but I'm quite concerned. Is the slimy stuff responsible for my fish deaths? How can I get rid of the green stuff?

Thank you.

[joannde]

Algae on the glass is actually common - it may only seem slimy because of water evaporation. Does it smell at all? If it smells like a polluted pond it may be BGA. If you haven't seen it in the tank I wouldn't think that it could kill your fish; and even if you DID see it in your tank, it may not kill them. I had a bad case of BGA in my 10G tank and lost only one fish (who I think ate some of the BGA).

Have you tested your tank parameters (ammonia, nitrites, nitrates) using a liquid reagent kit ?

[Fishyfanatic]

I get the exact same thing on the hood of the tank next to the airstone. It's just from the water splashing onto the hood. Scrape it off every few weeks. I can't attribute it to any fish deaths, but that doesn't necessarily mean that it is impossible. I've just never experienced it.

[Big C]

Thank you. Any ideas about why the fish are dieing in such a funny way?