Fighting fish parasites with photodynamically active chlorophyllin

Area of Science:

• Aquatic biology
• Parasitology
• Photochemistry

Background:

• Fish ectoparasites pose significant threats to aquaculture and pond health.
• Existing chemical treatments are often restricted or ineffective.
• Novel, safe, and cost-effective parasite control methods are needed.

Purpose of the Study:

• To investigate the efficacy of water-soluble chlorophyll (chlorophyllin) as a photodynamic agent against fish ectoparasites.
• To determine effective concentrations and conditions for chlorophyllin-based phototoxicity.
• To evaluate chlorophyllin as a potential alternative to chemical treatments in aquaculture.

Main Methods:

• Exposure of fish ectoparasites (Ichthyobodo, Dactylogyrus, Trichodina, Argulus) to varying concentrations of chlorophyllin.
• Application of simulated solar radiation post-incubation to induce phototoxic reactions.
• Assessment of parasite mortality rates at different chlorophyllin concentrations and light exposure durations.

Main Results:

• Chlorophyllin demonstrated significant phototoxic effects against Ichthyobodo, Dactylogyrus, and Trichodina at concentrations of 2-6 μg/mL.
• Specific lethal concentrations (LD50) were determined for Dactylogyrus (1.02 μg/mL).
• No significant effect was observed against the parasitic crustacean Argulus.

Conclusions:

• Chlorophyllin is a potent, light-activated agent against several common fish ectoparasites.
• Its non-toxic, biodegradable nature and low production cost make it a viable eco-friendly alternative.
• Chlorophyllin-based photodynamic therapy offers a promising solution for parasite management in aquaculture and ponds.