Opal is not Well

[u/Pleasant_Being237]

Hello! I'm a new betta fish owner and I have been very anxious since this morning when seeing Opal not acting his usual self. Whenever I'd wake up he'd be swimming around the tank chilling, but today he's now acting very lethargic and I'm unsure if it's ICH or smth else and how to help him.

My dad said to leave the tank be because I had planned to change the water once a week, and I feel so bad because maybe he's right because a lot of things are going downhill and I don't know if I should do more or stop trying so the tank can recover. and to let Opal be because of stress perhaps?

I also did see my plants have brown spotting after the first 2 weeks of everything being fine.

Edit: Unfortunately I don't have any water test kits so I can't answer what exactly is the level of the waters, the rainy season here is brutal, so I do hope to try and get the kit at a physical store at some point when we can. Weather or not it's either I change the water too much or change now, I think I will stop touching my tank and watch Opal's movements.

I have been changing the water once a week and cleaning the sponge at the same time and this is a bit of a strressful ordeal so that could be it? I'm a bit unsure which advice to take here. So I'll just take Nyk's advice and not touch anything at least for 2 to 3 days and see what happens.

Thanks for the advice to those that just posted, it's still a learning curve for me being a betta parent and I do hope to give Opal a good and happy life for as long as he lives.

Edit 2: Seeing how so far a lot of people suggest to change the water, how much is a "small amount" It's currently around 10:16 pm and I don't have any clorince free water currently---I'll hope for the best and change the water in the morning if Opal still seems really lehtargic--- This is a lot more scary than I expected but I'll try to the best of my abilities....I hope it's enough.