I think if they have stopped eating they could have a bacterial infection, bloodworms can be funny, plus how often do you do a gravel vac with bottom feeders it wise to do two a week, as if they eat contaminated food they become ill which also can lead to fish tb.
With the way they are it would be wise to put them in isolation.
Can you issolate them, is every single plec in the same way, have they all lost weight as well, trying to find out if it's a parasite or bacterial.
This info has been taken off the emergency board on this site.
Tuberculosis
A fairly infectious bacterial disease, tubercolosis is becoming incresingly common. Affected specimens must be removed from the aquariym immediately so that other fishes aren't infected. A tubercular fish usually feeds normally, but loses weight as it's internal organs become damaged. Some fish develop nodules under the skin which eventually ulcerate, in other nodules develop behind the eye, causing "pop-eye".
The bacteria that causes the disease prefers cooler temperatures than most bacteria that infect humans. However, fish tuberculosis can affect people, usually in the for of an infected nodule on the skin, but there is a small chance that it will cause a serious internal infection. nce diagnosed in one of your fish, strict hygienic precautions should be observed. A definate diagnosis is only possible by a post mortem.
Things To Look Out For
Appears dull in colour
Weight loss
Folded fins
Ulcerous skin wounds
Treatment
Seek vetinary advice. Affected fish should be removed and euthanized. Don't allow them to die in the tank as other inhabitants will eat them and become infected too. The tubercular fish's contacts should be treated: move them to a separate hospital tank, and disinfect the original aquarium. If other fish succumb, don't introduce any new specimens, euthanize all affected fish then clean, disinfect and re-stock the aquarium.
This has been taken from the board.
Internal Bacteria
Symptoms
a. In some cases fish will darken in colour, become listless, stop feeding and die.
b. In other cases, severe symptons exist, ulcers, abdominal (dropsy) and eye swelling (pop eye), destruction of the central nervous system and then the fish dies.
Influencing Factors - Poor water quality will stress the fish and make them susceptible to infection. Also fin and body tissue damage will give the bacteria a site to start infecting.
My Experience -I recently lost one of my Mollies she was black so i did not notice her darken in colour, but she hid all the time and stopped eating, then died. At the point she died four other mollies and two platies started to hide and not eat. Also around this time started to notice that some of the fish had long stringy white feces (poo), it was 5 inches long in some cases.
I did a 30% water change and added Interpet No 9 for internal bacteria, plus two spoons of salt. Next day I added two more spoons of salt. On day four I put in the second dose required of Interpet No 9. Then nothing else and no water changes for the next 8 days. On the day four (after second dose) one of the mollies passed a lot of white gooey stuff and after that he started to come out at feeding time and occasionally take one or two nibbles.
All fish were fine at the end of the 8 days, out from hiding and eating again. Some did however still have a bit of stringy poo. I was therefore advised to do a 25% water change and clean up and redose the medication without salt. This is mainly as a precaution because the disease can come back if it is not "completely" cleared up.
Reason it happened - I did not know at the time buy my pump housing was blocked my pump hardly running at all. My water parameters did not show there was a problem but the pump must have been getting slower and slower over a period of time and therefore the oxygen was getting lower and lower. I believe this is what caused the bad water conditions that kicked in the infection for my fish.
What I have learnt - Fish commonly get ill because of poor water quality. I knew I had not introduced anything new, I did regular water changes and my tests were all good. How could it be poor water quality. It was because of the pump problem. I say don't give up looking there is always a reason, don't just treat the disease, find out why and learn from it.
