Okay if he is looking unwell then the next step is to work out why.
Have a look over his body, do you see any fluffy or slimy stuff on him anywhere? If you shine a light on him does he appear to shine gold like someone poured glitter on him?
For the time being I recommend that you keep his water clean and wrap his tank/sit it on a blanket or towel, this will speed up the usefulness of his heater and help to keep the water's temp steady.
If you see signs of itching (he will ram into things or smack himself about to try and scratch) or his appetite doesnt come back soon we can begin looking into possible illnesses he may have gotten at the pet store.
It's harsh to declare that without a heater a compromised Betta will die. None of us knows that with any certainty and, IMO, it's a incredibly cruel to make an already distressed owner feel even more helpless and guilty.
To the OP: I hope your Betta will recover. However, if he does not please know his lack of a heater will not be the cause and don't let anyone tell you it is.
Last edited by RussellTheShihTzu; 06-23-2014 at 08:52 PM.
My fish is my highest priority right now, and my parents are cheap, cheap people who do not understand what a fish needs. I will try my best to keep the fishes temperature at a constant 76-80. His fins are red at the tips, I'm not sure if it just his natural coloration or ammonia/fin rot. He does not have a gold speckled or fungusy body.
Hence why keeping something around the tank is a great idea. also when cleaning it next pop a buffer like a towel or washcloth underneath it- this prevents heat being sucked out into the table underneath.
If he doesnt appear to have any outward signs of infection then he can either have something internal or be responding to stress. In the pictures you submitted he does not appear to be clamping which is good, have you seen him folding al his fins close or getting a war stripe behind his eye/along his body?
By the sounds of for now he is merely feeling a little overwhelmed. I recommend giving him 4-7 days to settle in and see if his behavior settles down, if in that time he starts to stripe up or scratch it may be something else.
Keep us posted