Sorry you're dealing with this. Clowns do sleep and hang out in some weird positions, but one that's spending more and more time on its side and moving less is worth taking seriously, especially with ammonia in the picture.
A few things I'd check:
- Retest ammonia with a second kit, or have your local fish store test a sample. A real 1 ppm reading in a tank that's been running six weeks usually means the cycle isn't fully done or something is rotting, like uneaten food or a dead snail or hermit.
- Test nitrite too. Until both read zero, feed lightly and keep up with water changes, matching temperature and salinity on the new water.
- Get the surface moving. Aim a powerhead or the return so the surface ripples. A fish that hangs at the top can be telling you oxygen is low.
- Check salinity with a calibrated refractometer. Swing-arm hydrometers are often off.
- Look closely for spots, cloudy eyes, fast breathing or white stringy poop. If you see any of that, post a photo or short video here and we can help narrow it down.
The fact that it's still eating is a really good sign. Let us know what the second test shows.
Mike / Blue-Eyed Clowns