Hi everyone,

I did a partial water change this evening, and I noticed my female swordtail wasn't looking too good, she's swimming near the bottom and breathing pretty fast. All of the other fish seem fine.

I tested the water levels:
ph 7.0
ammonia 2.0 ppm
nitrite 0 ppm
nitrates 20 ppm

I also changed the filter. I don't have anything to bring the ammonia level down straightaway, I'd have to get something tomorrow.

Are the high levels of ammonia and nitrates related to my fish being sick?

General tank info:
20 gal
1 female swordtail, 2 female platies, 2 tetras, 2 female mollies, 1 male molly
I know my tank is a bit overstocked, I could switch some over to the spare 10 gal I have if it would make a difference. Let me know what you think please.

I don't think the nitrates are that high, just the ammonia would be worrisome

__________________
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I would not use anything to take care of an ammonia problem except a water change. Chemicals are not good. You should do at least a 50% water change to try and get the ammonia down. If 2ppm is what you read after your water change, then who knows where it was before. The Swordtail acting this way is probably from the ammonia being so high, not the other way around.

How long have you had your tank setup and how long have fish been in it? Sounds like it is still cycling. Are you using ph products in your tank?

I've had the tank set up for 2 months here since I moved, I had it set up for 2 months before then, so about 4 months. I use ph tablets to keep the water ph stable. I will do another water change to see if it helps.

Ph tablets may be your issue also. The fish will be fine without..and better off. What is your ph? What do the tablets do for you?

The ph tablets help keep the water ph from going too low. My tank is planted and sometimes the ph went to low because of the plant substrate.My ph is 7.0. What is wrong with using ph tablets?

Also I just did a 50% water change, the ammonia dropped to 0.50 ppm. When should I do another change?