Hi all,
Thanks for your help. Filled out all the profile stuff, it's a 160L (about 40-45 gallon) tank. All the fish are still fairly small, and the water quality is good as far as I can tell, but I've never checked hardness as the tap water here is pretty soft anyway. Filters are all clean and in good condition.
I treat the tap water with
chlorine neutraliser and leave it for 1-2 days before adding to the tank.
I did have a problem with brown algae a while ago, but seem to have got rid of that with some suckerfish and by keeping the light out of the overhead filter.
I can't see any obvious damage to fins, but will keep a closer eye on the water quality & see if anything shows up.
It does seem to be the one that gets picked on by the more agressive angel, but I really don't know if that's the problem. The gourami is smaller than the angels and keeps to himself.
Anything else it might be?