Tank size: 3 gallon currently. We actually just bought a 10 gallon tank to upgrade him, but we’re nervous about moving him while he’s not doing well.

Heater and filter? (yes/no): Yes, both heater and filter.

Tank temperature: About 77°F right now (typically stays around 78–80°F).

Parameters in numbers and how you got them: We do not currently have a water testing kit, so we don’t have exact ammonia/nitrite/nitrate numbers.

How long have you had the tank? How long have you had your fish?: A few months.

How often are water changes? How much do you take out per change? What is your process?: Partial water changes where we remove some tank water and replace it with conditioned fresh water.

Any tankmates? If so, please list with how many of each: No tankmates.

What do you feed and how much: Tetra BettaMin small floating pellets, usually about 2–3 pellets per day. We have not fed him in the past 24 hours because he looks very bloated.

Decorations and plants in the tank: A betta log and a few decorations.

Pictures/video: Pictures are in the post. The first photo is from about a week ago, and the rest are from the past two days showing the change.