lautnusantara.com Definition of Fish Pests: All living organisms (animals)—whether smaller, the same size, or larger than the fish—whose presence is undesirable because they can cause disturbances. In other words, pests are organisms that prey on, disturb, or compete with fish within their habitat.

Definition of Fish Disease: A physiological symptom caused by parasites or unsuitable environmental factors. Diseases occur when a fish’s condition is weak and are influenced by the attack methods of the pathogen. While Tilapia are known to be hardy and disease-resistant—with massive outbreaks being rare—pests and diseases should never be underestimated. Farmers must remain vigilant at all times.

6 Main Types of Pests and Their Control

• a) Backswimmers (Notonecta): These are dangerous to Tilapia, especially small fry, due to their sting.

  • Control: Pour 500 cc of kerosene per 100 square meters onto the water surface.

• b) Water Tiger (Cybister larva): These larvae attack by pinching and tearing the fish's body with their mandibles.

  • Control: They are difficult to eradicate; prevent the accumulation of organic matter around the pond.

• c) Frogs: A primary enemy of fish eggs.

  • Control: Regularly remove floating frog eggs; catch and relocate adult frogs.

• d) Snakes: These prey on seeds and small fish.

  • Control: Manual capture and installing perimeter nets around the pond.

• e) Otters: Highly voracious predators that hunt at night.

  • Control: Install baited traps and fence the pond with sturdy netting.

• f) Birds: They prey on fry and small fish, and occasionally adults.

  • Control: Install bamboo barriers, overhead netting, or shiny ribbons/strings across the pond surface to deter diving.

4 Dangerous Diseases in Tilapia and Their Control

a) Parasitic Disease caused by Trichodina sp.

This parasite attacks the skin, fins, and gills. Symptoms include visible wounds on the affected body parts.

• Control: * Regular water changes and installing water filters (sedimentation tanks).

  • Soak infected fish in a salt solution (NaCl) of 500–1,000 mg/liter for 24 hours, or a formalin solution of 25 mg/liter.

  • Repeat treatment every 3 days until fully recovered.

b) Parasitic Disease caused by Epistylis spp.

This microorganism attacks the skin, fins, and gills. Symptoms include gills turning reddish-brown, respiratory distress, lethargy, and stunted growth. It spreads via direct contact.

• Control: * Isolate sick fish in quarantine ponds.

  • Maintain water quality and ensure stocking density does not exceed capacity.

  • Soak fish in 200 mg/liter of formalin for 40 minutes, or 20 mg/liter of $KMnO_4$ (Potassium Permanganate) for 15–20 minutes.

c) Fungal Disease (Saprolegniasis)

A fungus often found in hatcheries, attacking eggs, larvae, and fry. It appears as fine white to brownish-white threads on the body.

• Control: * Soak affected eggs or fish in 1 mg/liter Malachite Green for 1 hour, or 200–300 mg/liter Formalin for 1–3 hours, or 5 g/liter NaCl for 15 minutes.

d) Red Spot Disease (Aeromonas and Pseudomonas)

These bacteria attack both external and internal organs. Symptoms include bleeding on the body, peeling scales, ulcers, abdominal dropsy (bloating), and internal bleeding of the liver, kidneys, and spleen.

• Control: * Maintain water quality and avoid overfeeding.

  • Mix feed with Oxytetracycline (50 mg/kg of feed) for 7–10 days.

  • Injections: Tetramycin (0.05 ml per 100g of fish weight) or Kanamycin (20–40 mg/kg of fish weight).

5 Main Factors Causing Disease

Disease occurs when the interaction between the fish (host), the environment, and the pathogen is imbalanced. This imbalance causes stress, weakening the fish's immune system. Factors include:

1. Parasitic attacks.

2. Polluted environments (Ammonia, Sulfide, or toxic chemicals).

3. Drastic fluctuations in temperature, pH, salinity, and turbidity.

4. Inappropriate nutrition or feed.

5. Genetic weakness.

7 Tips to Prevent Disease in Tilapia

Prevention is always better than cure. To minimize risk:

• a) Clean and dry the pond bottom after every harvest.

• b) Use healthy, disease-free fingerlings.

• c) Avoid overstocking.

• d) Use parallel irrigation systems to prevent cross-contamination between ponds.

• e) Practice proper fish husbandry.

• f) Feed in moderation; leftover feed rots, creating $H_2S$ (Hydrogen Sulfide) gas and promoting pathogens.

• g) Change pond water regularly.

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