Mollusc Infestation - Fish Diseases Caused by Parasites

Mollusc Infestation

CAUSATIVE AGENT:

Glochidia is the larval stage of freshwater bivalve molluscs that may attachto fish. The margins of their shells have sharp teeth (Fig. 5-17).

SPECIES AFFECTED:

Freshwater fish

GROSS SIGNS:

The shell valves are attached to gills and outer surfaces of fish.

EFFECTS ON HOST:

The gill tissue is destroyed. The respiratory function of the gills during se-vere infestations is disrupted. Secondary bacterial and fungal infections result when the parasite leaves the host.

Diagnosis:

Gross macroscopic and microscopic examination of the host fish.

PREVENTION AND CONTROL:

•  Adequate filtration of intake water to prevent entry of larval glochidium