Barbs are ravenous eaters. My Black Ruby Barbs will eat so rapidly and then take in so much air from the surface doing it, they show effects. Worms of any sort are not good food for more than once a week, and bloodworms are especially so. Do yu mean frozen bloodworms, or dried (freeze dried)? Frozen are fine as a treat, once a week, no more.
I have heard of disease coming with bloodworms, but not experienced it myself. I use Hikari frozen bloodworms and frozen daphnia. Other foods are all prepared (Omega One, New Life Spectrum; neither of these have "meals" in them which are not good for fish either).
Water levels, can you always post numbers; we don't know what "fine" may actually be to you. Ammonia, nitrite, nitrate; pH and GH. On the nitrate, you say a little high, ready for a water change...water changes should not be determined by tests, but regular. But on the nitrate, if it is rising between water changes it is a problem. Assuming nitrate is not present in the source water, do more water changes if you see nitrate increase from one WC to the next. WC's should result in more stable levels for nitrate and pH. Overcrowding, overfeeding, too few WC's, not cleaning the filter, not cleaning the substrate are all causes for nitrates occurring within the aquarium. Nitrate should remain absolutely the same for weeks, months. If it doesn't, then look at these possible issues, and increase the volume changed. I change 60% once a week, and I have stable pH and nitrate and have done for years now.
Bloating could be due to much of the above. Feed blanched peas; blanch some fresh or frozen peas (not canned), remove the outer husk, and feed the inner pulp. No other foods for a few days. If this is bloat, this may clear it. Then watch the foods after that.
Byron.
