Emergency?!! Please help. What kind of sickness does my betta have?

[Rainnn]

So long story short, it's my families fish, though I am mostly responsible cleaning it. It lives in a 3.5 gallon tank. Family refuses to get anything bigger. It doesn't have a filter, I clean it out completely once a week.

I had another betta for over 3 years but it died, not sure why.

Anyway, this betta was a bright blue color when I got it. I've had it for about 6 months.

It's developing these white/peach colored marks all over his body. I don't know what it can be since I keep the tank really clean all the time. I also noticed one of it's fins is "ripped" looking. It did not, I repeat DID NOT, look like this until a week or two ago.

What can I do?

Please answer asap!

Here are some pictures.

 

[Greta1981]

A betta can live in a 3.5 gallon, but it MUST have a filter and a heater. The lack of a filter prevents the natural nitrogen cycle from establishing itself. Cleaning a tank out completely is never recommended because it disrupts that same cycle, built on beneficial bacteria. Do you know your ammonia, nitrite, and nitrate levels? What are you using to condition your water? How many times a week are you changing the water?

The more details you give us, the better we can help you. I suspect your betta is suffering from ammonia and nitrite poisoning, based on the poor condition of his fins and the black spots on his body. I'd recommend an immediate 30% change of water, with water conditioner, temperature-matched to the tank, then another 30% in two hours. However, the only real way to ensure your fish makes a full recovery is to give him the heater and filter that he so badly needs.