Hello all. This is only my second post so bear that in mind please I have a fish with swim bladder problems. He's a smallish fantail (I think - he only has one tailfin rather than the double fan, but the rest of him matches a fantail) and for the last three days has been alternating between being fine and struggling to stay off the bottom of the tank. I just checked the water. I only have a simple test kit using color-changing swatches, so it doesn't give precise readings but: NO3 - between 50 and 100 mg/l (on the threshold of the 'water change' zone of the kit) NO2 - 0 mg/l (safe zone) General Hardness: 8*d-16*d (safe zone) KH: 3*d-6*d (safe zone) pH: 6.4 Cl: 0, possibly somewhere between there and 0.8, it was hard to tell. It may be a little high as I used up all of my aquasafe during the last water change and had to be a little sparse. Their last water change was on Sunday, for about 10-20%. I change the water each Sunday by vacuuming the gravel and messing it up to get all the dirt up, using a simple pipe siphon. My question is: what can cause high NO3 (I think that's Nitrates?) but low NO2 (nitrites?). I was under the impression that usually when one is high, the other is too; apologies, I read up on this a while ago but I've gotten rusty again, so I can't remember how the nitrate system works. How do I go about treating it? I read I should try and put more plants in and do more water changes (currently weekly) until then? They currently only have one live plant as they picked at the rest until the stems broke and they floated up to the top of the tank, separate from their roots. I live in the UK, so proper fish medicine and treatments are hard to come by. If you're of the opinion that it's not the nitrates that's causing my fish (Brian)'s swim bladder issues, what else could it be/should I do? They have been starved for a day to see if it's constipation but my head is telling me that since he keeps oscillating from fine to sunken, it's something other than constipation - is this illogical? Thanks, Erika.