Can heat kill fish and/or snails? It has been unusually hot here these last few days and I have been doing small water changes everyday so the water wouldn't get too warm but I missed one this morning as I has to go to work, went to do one before I went to sleep and noticed my bladder snail that is in the 28 litre tank was on her back and not moving, I beleive she is dead as she is normally incredibly active, could it have been the heat? The apple snail in that tank also seems to be a bit subdued but the platy's seem normal. If it is the heat how can I counter act it?

Yeah they are in my bedroom so no ovens, they are near a radiator but it is never switched on and near the windows but I never open my curtains. Should I keep doing small water changes everyday just to cool the water down a bit?

I don't think you need to be so worried about temperature, fish live in nature, and in nature, the temperature changes a few times every year. If there isn't anything that could have a sudden impact on temperature around, I think you should just continue with normal weekly water changes as if nothing happens. I've done so all my life so far and I haven't had any fish die/get sick because of warmer weather

Vic, my bladder snails have been absolutely fine with this heat, at least I can't see any empty shells around.
I have had some of my bladder snails die in the past, at varying ages and I still don't know why those one's died, when everything was fine.

Overall I've had 10 snails die, in the 6 or 7 months that I've had them. Some of the shells are large, so it could be age. Some of them are quite small, so it could be that as young snails, perhaps they were out competed for food in some way. I just honestly don't know!

I wouldn't worry too much about it at this stage, if water quality is good and everyone else seem's okay
I have just altered my tank and care in accordance, so giving them a nicer prettier tank and adding Cuttle fish to supplement calcium, making sure there is always a source of food in the tank, so I know the little one's will have chance to eat

I'm possibly going to sort out a filter for the little guys as well!

Have you tested the water?
It might also be as simple as a lack of oxygen in the tank during hotter weather. Try to adjust the spraybar/outtake of your filter and see if that helps making the surface move more

I heard that chilling the water too much could promote breeding. Is this true?

I wouldn't worry if it was true Vicloz because your only putting in a peice of ice.

Well the fish were fine throughout the hot weather it was just the snails that seemed to be bothered. I lost two bladder snails in total.

Cheers Nossie!