Wow, that's one for the books. I've had critters left on my doorstep, but never a fish. Probably some kids mother told him to find it another home. So glad you took him in and are caring for him. If the city is posting about impurities in the water then it's a good guess that it's a good part of what is making him sick. So that we have more background can you please fill out the questionaire below.
And if by yellow container...you mean Tetramin flakes, it's not the best thing to be feeding him, it's not nutrionally complete for a betta. He needs a good pelleted food such as New Life Spectrum betta. Eating flakes he can ingest a lot of air along with the flake and that isn't good. Also, it is harder to keep track of just how much you are feeding him. A betta's stomach is only the size of his eye, and if overfed he can become sick. Problem with bettas is that they are little water piggies......they will keep eating and have you think they are constantly starving.
Housing
What size is your tank?
What temperature is your tank?
Does your tank have a filter?
Does your tank have an air stone or other type of aeration?
Is your tank heated?
What tank mates does your betta fish live with?
Food
What type of
food
do you feed your betta fish?
How often do you feed your betta fish?
Maintenance
How often do you perform a water change?
What percentage of the water do you change when you perform a water change?
What type of additives do you add to the water when you perform a water change?
Water Parameters:
Have you tested your water? If so, what are the following parameters?
Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:
Symptoms and Treatment
How has your betta fish's appearance changed?
How has your betta fish's behavior changed?
When did you start noticing the symptoms?
Have you started treating your fish? If so, how?
Does your fish have any history of being ill?
How old is your fish (approximately)?
