Who Gives A Fish Forums

I'd also look at the flow from your sponge filter. Bettas prefer calm water, and if the flow's too strong, it can stress them out. You might need to baffle it with a pre-filter sponge or adjust the air pump.

Mine hated tap water even with conditioner. Switched to RO and he's way more active now. Maybe your local water's got something sketchy in it.

Neons are cheaper and easier to find, but Cardinals handle higher temps better if your room gets warm. Both need stable water, though. Test your nitrates weekly—they're sensitive to buildup.