By the way, have you tried Metronidazole?
According to the website below,
Metronidazole combine with Neomycin can treat fish bloating of digestive tract.
Probably a combination of both is more effective.
Aquarium & Pond medications Part 2, antibiotics and antimicrobials such as Kanamycin, Triple Sulfa, Tetracycline, Metronidazole, Nitrofurazone, Neomycin, & more. Based on research from aquarium keeping guru Carl Strohmeyer
www.americanaquariumproducts.com
METRONIDAZOLE:
USE: Metronidazoles primary use is for the treatment of anaerobic gram positive bacteria including those that produce beta-lactamase. However, it is not effective against aerobic bacterium.
As well Metronidazole is effective for some protozoa (especially internal flagellates).
Due to Metronidazole effectiveness against anaerobic bacteria (by selectively blocking some of the cell functions of anaerobic bacteria) this drug along with Neomycin is a good choice for bloating of the digestive tract (common in goldfish). Metronidazole when combined with Neomycin sulfate in a medicated fish food slurry can be a very good full spectrum internal/gut infection treatment, treating both aerobic and anaerobic bacterium.
Metronidazole selectively blocks some of the cell functions in anaerobic bacteria, resulting in their demise.
NEOMYCIN SULFATE:
USE: Neomycin (a Aminoglycoside) is a broad spectrum antibiotic that is effective for aerobic gram-positive, some gram-negative such as Aeromonas of the gut, and occasionally Mycobacterium tuberculosis (
Mycobacterium marinum), which is neither Gram-positive nor Gram-negative due to high lipid content in its wall.
Neomycin is poorly absorbed internally. The lack of absorption from the gastrointestinal tract is the basis of the main use of Neomycin.
Effective for some Gram-negative bacteria- Open red sores or ulcerations, intestinal infections, fin and tail damage. As noted, Neomycin can be effective for wounds, ulcerations, or large sores, however I have found best results when used in combination with Triple Sulfa for such issues (used in a fish bath at double dose can also yield better results).
In severe cases where fins and tail are eaten away- treat with Kanamycin for this.
As well, Neomycin can be PART of a treatment for mycobacterium tuberculosis (symptoms, weight loss, a distended abdomen, loss of appetite, fin erosion, unusual coloration, spinal deformities, and listless behavior).
Aminoglycosides such as Neomycin are mostly ineffective against anaerobic bacteria, fungi, yeast, and viruses.
Neomycin is not absorbed by the intestinal tract and is effective in treatment of diseases thereof. But Neomycin can damage the kidneys as it is nephrotoxic when it enters the bloodstream, however since this drug is not readily absorbed in the intestinal tract it is useful for treatment of pathogens such as Aeromonas, particularly of the gut, that can lead to Dropsy or similar disease.