Is your tank cycled? It could be some form of poisoning and finrot for sure. He needs to have some medication like Maracyn and Maracyn2 together. The temperature of your tank also needs to be about 82 F or 28 C and he will need to have extreemly clean water and tank conditions during the process of treatment. I believe that the Maracyn2 specifies not to do water changes during the treatment so please make sure that the tank is cycled and then I would also do a pea treatment for possible constipation.
If the tank is not cycled, do a large
water change before adding the medication and remove the carbon from your filter or it will remove the medication before it can even do anything.
The pea treatment is done as follows:
Take one frozen pea and put on a saucer and defrost it in the microwave with no water ~ 30 seconds or so.
Skin the outer skin off the pea.
Slice a small piece half the size of his eye into 3 pieces or so. Feed them to him. Do not feed any other fish food or anything while you are doing this as they need to be cleaned out. If he will not eat the pea, leave him with no food of any kind for 1 day and then try again. They turn up their noses at the peas until they have tried them and usually then they love them.
If you have not tested your tap water for
ammonia, nitrites and nitrates straight out of the tap yet you may want to do so as it could be a problem with the tap water. I lost a betta to tap water quality problems one time and it was a shock and happened overnight the same way you are talking about. Do not put anything in the tap water, just test for ammonia, nitrites and nitrates and please post the results.
Please let us know how he is doing. I am so sorry this is happening to him and you.
Rose
