a. Ciprofloxacin

b. Ofloxacin

c. Nalidixic acid

d. Oxolinic acid

All the above belongs to Fluoroquinolones that inhibits DNA topoisomerases (DNA gyrase and topoisomerase 4) by binding to DNA-enzyme complexes, thereby interfering with bacterial DNA replication and some aspects of transcription, repair, recombination, and transposition. Fluoroquinolone antibiotic with a broad spectrum of action and they work against a wide variety of bacteria. These antibiotics work best at acidic pHs of 6.9 or less, and they are inhibited by hard water. Although they appear to work well in both bath and oral treatments, some fish / shrimp may sink to the bottom and appear lethargic after bath treatments.

e. Chloramphenicol

It is a broad spectrum antibiotic. Chloramphenicol inhibits protein synthesis by binding to 50S ribosomal subunits, preventing binding of amino acyl t-RNA and inhibiting polypeptide synthesis.

f. Doxycycline

g. Oxytetracycline

The above antibiotics belongs to Tetracyclines which they inhibit protein synthesis by mainly binding to 30S ribosomal subunit and blocking binding of aminoacyl transfer-RNA. They are considered broad-spectrum antibiotics (effective against a wide variety of bacteria) and they work well when mixed with food. However, bath treatments may not be as effective for all species. These antibiotics upon increasing water hardness (i.e., increases in calcium and magnesium levels) it is necessary to increase the dosages required for these drugs to have any effectiveness as bath treatments. Tetracyclines are ineffective when used as a bath treatment for saltwater fish / shrimp. Water should be changed immediately after the bath treatment period is concluded.

h. Erythromycin

Erythromycin belongs to the group of Macrolides which inhibit protein synthesis by binding to 50S ribosomal subunits, inhibiting translocation of peptidase chain and inhibiting polypeptide synthesis. This antibiotic is most effective against gram-positive bacteria. Also, erythromycin is not very effective in a bath treatment and should only be administered by mixing in to the feed. Since the drug gets partly destroyed by the gastric acid, the ester forms (Estolate and Stearate) are given.

i. Streptomycin sulphate

j. Kanamycin sulphate

k. Neomycin sulphate

l. Gentamycin sulphate

All the above antibiotics are belongs to the group of Aminoglycosides which inhibit protein synthesis by irreversibly binding to 30S ribosomal subunit. The aminoglycosides are very effective against gram-negative bacteria infections when administered. Unfortunately, this group has also been shown to cause kidney damage in fish when administered. As a group, these antibiotics are not considered effective when used in oral or bath treatments. A couple of exceptions may be Kanamycin and neomycin, both of which may be effective against external infections if used in bath treatments. In addition, Kanamycin is also believed to be effective when mixed with feed to treat gastrointestinal bacterial infections.

m. Furazolidone

n. Nitrofurazone

The nitrofurans, including Nitrofurazone and Furazolidone, are commonly used in the fish / shrimp trade. They normally interfere with several bacterial enzyme systems, possibly including prevention of acetylation of coenzyme A.

Although nitrofurans are commonly used in bath treatments, they are probably most effective against superficial infections. Within the group, Furanace appears to be the most effective for use in bath treatments. To achieve the most effective result when using a nitrofuran in a bath treatment, either some sort of cover or the treatment location should be considered, as the nitrofurans can be inactivated by light. Nitrofurans as oral treatments may not be as effective as previously believed, although the proper pharmacokinetic research needs to be performed to verify this conclusion.

o. Rifampisin

Rifampicin is an anti-mycobacterial drug that is semisynthetic derivative of rifamycin antibiotics which are produced by the fermentation of a strain of Streptomyces mediterranei. It is also useful for elimination of Neisseria meningococci in carriers (but not recommended for active meningococcal infection) and for Gram positive (Staphylococcus aureus and epidermidis, Streptococcus pyogenes, viridans and pneumoniae) and gram negative bacteria (Haemophilus influenzae type B). It has some anti-chlamydial activity and in vitro activity against some viruses (poxvirus and adenovirus) at high doses. Rifampicin may be bacteriostatic or bactericidal depending on the concentration of drug attained at site of infection. The bactericidal actions are secondary to interfering with the synthesis of nucleic acids by inhibiting bacterial DNA-dependent RNA polymers at the B-subunit thus preventing initiation of RNA transcription, but not chain elongation.

p. Prefuran

Prefuran is nifurpirinol, belongs to Nitrofuran group, which is synthetic antibacterial. They have antibacterial and antiprotozoal activity and have been used extensively in fish and shrimp farming.