DISEASES OF AFRICAN MAGUR SEED
| 1. Symptoms: | Normal dark-brown color of fish becomes lighter. Sporadic and later mass mortality. Barbels are not straight. Some barbels are shorter than others. Knob may develop at the end of it. Different-size whitish areas can develop on skin, mainly around mouth. The edge of fins may frayed out at some places. Fins may store between the rays. Fish hanging in vertical position at water surface if the infection is strong. |
| Pathogen: | Myxobacteria |
| Treatment: | Antibiotic and formalin bath in tray. Antibiotic (see below) mixed in feed advised to use in pond. |
| Remarks: | The disease can be controlled in initial stage without significant mortality. If the treatment is not satisfactory, or the disease is recognized too late, mass mortality occurs. Treatment of fish in pond less effective because infected fish do not consume feed containing antibiotic. (No bath treatment can be done in ponds, because medicines are expensive.) |
| 2. Symptoms: | Whitish (cotton like) infected areas on the body surface. |
| Pathogen: | Saprolegnia |
| Treatment: | Malachite green or formalin bath. |
| Remarks: | Saprolegnia infection may occur after sampling or harvesting. It is particularly dangers under 20°C. |
| 3. Symptoms: | Color of fish becomes grayish-white. Significant number of fish stay in vertical position near to the surface of water. Tears on the fins are certain symptoms of the infection also. |
| Pathogens: | Protozoa, or other parasites. |
| Identification: | Microscope with 100–400 magnification is essential for exact identification of Protozoa infection. For diagnosis of worm-type parasites a 25–40 times magnification is sufficient. |
| Treatment: | Salt, formalin and Malachite treatment are suitable for control of Protozoan infections. Organophosphate (Dipterex) or NH4OH baths are effective against worm type parasites. |
| 4. Symptoms: | Swelling of necessary breathing organ and/or the belly. Inflammation in the mentioned organs. |
| Pathogen: | Bacterial infection of fish enfeebled by adverse effect of environment. |
| Treatment: | Improvement of environment with water exchange, decreasing feeding level, liming with burned lime. |
CHEMICAL TREATMENTS:
Formalin (40% formaldehyde):
Suitable for controlling of bacteria and external parasites. Frequent application of 1 ml/10 liter is suggested for prophylaxis avoiding bacterial infection. Duration of treatment is 20–45 minute in tanks without water current. For controlling parasite infection short baths 2ml/liter (for 2 minutes) or 0.2 ml/liter (45 minutes) are suggested.
Kitchen salt:
It is used for treatment of fish infected by protozoa and other external (worm type) parasites. For profylaxis in the hatchery nursing daily 100 g/ 100 liter is suggested. Salt solution (1–3 %) using for short bath (for 1–5 minute) can eliminate infection of protozoa and some other parasites.
Malachite green:
It is effective on saprolegnia infection at the rate of 0.05–0.1 mg/liter, as a frequent treatment. It has some bacteriostatic effect also. For fish older than larval stage, 0.5–1.0 mg/liter concentration is suggested for 3–4 hours to control protozoa infection.
Ammonium hydroxide:
It is suggested when no other treatment can control external parasites other than protozoa. 1ml/1 liter is the allowed concentration, for 0.5–1.0 minute bath. Slight overdosing or prolongation of treatment can cause mass mortality.
Furazolidone:
The most effective agent to control Myxobacteria infection as a frequent treatment at the rate of 10–30 g/ 100 liter. It is suitable for treatment of fish mixed in food (50–70 mg/ kg biomass of fish daily for 10–15 days period). Overdosing after development of accessory breathing organ may hamper breathing.
Other antibiotics:
For control of external and internal bacteria infections other antibiotics (tetran, chloramphenycol, penicillin) are suitable also. The application is similar to that of furazolidone.
(The Appendix 4 was based on works of Molnar and Szakolczai, (1980); NIFI (Anon., 1981) and Janssen, (1987).)
