Betta with Clamped Fins

[Helyanwe]

I have a 5 gallon fluval chi tank, we noticed today our half moon betta's fins are starting to clamp together and hes laying around the bottom. We checked the tank and the Nitrites and Ammonia were really high, like top of the charts high. We dont know why the tank has spiked, it was cycled long ago, but we did a 75% water change, added Prime and Aquarium Salt to the tank.
Is there anything else anyone would suggest to save our betta?
Thanks

 

[Mumma.of.two]

Welcome to AA. Make sure to keep testing and changing water to keep ammonia and nitrite as low as you can. If its kept low he should (hopefully) recover. Have you changed anything in the tank recently? Filter? Substrate? Do you have any other tanks to borrow some media from?

 

[Helyanwe]

I did, I changed the substrate from gravel to dark sand because the ghost shrimp were hiding food in the gravel causing it to mold. So i put in black sand and a live plant.
I have a few established tanks, they are large tho so best I could do is drop the used media into the water.

 

[Mumma.of.two]

Sounds like the substrate change caused a mini cycle. It should sort itself out soon. The used media will help heaps.