Angelfish Suddenly Acting Weird

I just had an Angelfish that died about a month ago, but my other angel is still alive. He's been really healthy all his time, and he was doing really well. I decided to do a bit of a re-scape in my tank with some live plants and a new light. I added this yesterday. This stirred up a bunch of poop (not enough to cause ammonia, but it made the tank cloudy for about half an hour). Today, he's acting weird. I assumed he was being fussy until I added food to the tank. He's not eating. Now, he's sitting at the back of the tank, but not piping. There is plenty of oxygen in the tank. He's kind of acting like my other angelfish a month before who died.
There is plenty of oxygen in the tank, and I have two filters (one I am cycling for another tank). There is an airstone in there with air pump and all.
Ammonia: 0
Nitrites: 0.25 (calculations from friday)
Nitrates: around 100ppm (not that good)
I'd think that it it's water quality, other fish would be acting weird as well.
How can I treat this? I've tried varied diet, and he's still not eating that. Strangely enough though...he's gotten fatter.

 

For one, any nitrites at all in a tank is bad. Two, nitrates that high can stress fish out. I'd do two 50% WCs back-to-back to get those parameters in better shape ASAP. Just because all of your fish aren't displaying stress, doesn't mean they aren't feeling the effects of bad water quality.

Planting a tank and adding a new, bright light can also be stressful. He may just be struggling to cope with the bad water quality, and the stress of all that change at once.

If he's gotten "fatter", he might be a bit bloated. If it doesn't clear up soon, you might try some deshelled peas. Helps with constipation.

Overall, I think he just needs better water quality and time to adjust.

 

I agree that it's probably due to the water parameters. How often do you change the water and how much do you change?

 

For one, any nitrites at all in a tank is bad. Two, nitrates that high can stress fish out. I'd do two 50% WCs back-to-back to get those parameters in better shape ASAP. Just because all of your fish aren't displaying stress, doesn't mean they aren't feeling the effects of bad water quality.

Planting a tank and adding a new, bright light can also be stressful. He may just be struggling to cope with the bad water quality, and the stress of all that change at once.

If he's gotten "fatter", he might be a bit bloated. If it doesn't clear up soon, you might try some deshelled peas. Helps with constipation.

Overall, I think he just needs better water quality and time to adjust.

I've been using prime to help. I do know that nitrites are bad, but my tank is still doing really well.
However, I have good news! He started eating again!

I agree that it's probably due to the water parameters. How often do you change the water and how much do you change?

Usually a 15-20% water change every 1-2 weeks. Our tank had to recycle after our old filter broke.

 

Prime doesn't really do too much for Nitrite, and it isn't a substitute for clean water.

I'd bump that water change schedule wayyy up. Think more like 30-50% weekly to keep your nitrates under control. It's very difficult for a tank to be healthy when it's not completely cycled.

Glad he's eating again!