Forgot to turn on betta heater after water change

[kalynd]

I did a water change yesterday and I'm really kicking myself - I forgot to turn the heater back on. My betta's still adjusting to his new environment and now he's hovering at the bottom, looking pretty weak when he tries to move. The house and tank temperature's at 59 F right now, which is way too cold for him.

I've turned the heater back on, but I'm worried I might've caused some damage. I don't want to make things worse, so I'm not sure if I should let the heater warm the water up gradually or if that's too slow. Should I do a small water change with slightly warmer water - say 3 F degrees - and repeat that in half an hour or an hour? What's the best approach here?

I was trying to do everything right, cycling his tank and all that, but I guess I just messed up.

[SeaBidder]

I'd suggest adding a small amount of warmer water every hour or so, just a few degrees at a time, for the next few hours to help bring the temperature up more gradually. Then, once it's closer to the desired temperature, you can let the heater take over from there.