Is it safe to put a bottle of frozen water into a fishtank to cool down the water or will the sudden drop in temperature affect my fishes health? My water temp is around 80 degrees F which Im pretty sure is safe but its at the top end of my thermometer so I am getting concerned that anymore raises will completely destory my tanks cycle.

Cheers

That's one method of doing it, or ice cubes in a baggie. You could
leave the hood open and blow a fan across the top. If you have
an external canister filter, you can place it in a styrofoam cooler and
add ice cubes to that. If needed, you can turn the light off for the
tank. That's the majority of the ways to cool down a tank, other
than getting an expensive chiller($300+).

heh i dont think my tank has ever been that cold My fish dont know the meaning of cold. I wouldn't worry about it at all man, messing with ice n stuff might just give you bad temp swings if your not careful.

Thanks for both of your help. There isn't a problem now so I think I will leave the water has it is. If the fish start steaming and I start to smell cooked fish then I may give it a try then

Just make sure you have plenty of aeration in your tank, or lots
of plants. The higher the temp the less oxygen. For dealing with
Ich, it's recommended to raise the temp to 80 and dropsy to 84.
You should be fine at the temp you've got.