I'm back into the hobby after a long hiatus. Previously I had harder water, so I'm not used to current tap water which has little to no hardness at all. I have a 38 gallon tank stocked with 3 male platies and 16 tiger Barb's (8 regular, 6 green platinum, and 2 Starfire Red GloFish). I clean it once every 2 weeks, syphon the gravel, and do 30 to 60 % water change. The tank is almost 4 mos old.
My fish don't seem to be thriving. I've tried an airstone, aquarium salt, a ph adjuster, and beneficial bacteria. The tiger Barb's don't seem as active as I think they should be (i.e....a handful of them just hanging out not moving much for large portions of time du ing the day, unless I get close to the tank).
My question is, should I adjust my tap water to suit the fish, or get fish that are suited for my tap water? I feel like I have the perfect water for a Discus but my tank is too small. What other fish are good in water this soft and acidic ph (6.0-6.5)?