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Algal dermatitis in cichlids.
Roy P E Yanong1, Ruth Francis-Floyd, Eric Curtis
1Department of Fisheries and Aquatic Sciences, College of Agricultural and Life Sciences, University of Florida, Ruskin 33570, USA.
Summary
Algal dermatitis caused by Chlorochytrium spp. and Scenedesmus spp. affected ornamental cichlid fish in Florida. Standard algaecide treatments were unsuccessful in clearing the infections.
Area of Science:
- Aquatic pathology
- Ichthyology
- Algology
Background:
- Multifocal green lesions were observed in Pseudotropheus zebra populations on two Florida fish farms.
- Infection rates ranged from 5 to 60%, with fish otherwise appearing clinically normal.
Purpose of the Study:
- To diagnose the cause of green lesions in Pseudotropheus zebra.
- To identify the specific algae involved and assess treatment efficacy.
Main Methods:
- Diagnostic evaluation of affected fish.
- Microscopic examination of lesions (fresh and fixed).
- Identification of causative algal species.
Main Results:
- Algal dermatitis was confirmed, with light internal organ invasion.
- Farm A infected with Chlorochytrium spp.; Farm B infected with Scenedesmus spp.
- Bath treatments with copper sulfate pentahydrate, diuron, and sodium chloride were ineffective.
Conclusions:
- This is the first report of algal dermatitis in ornamental cichlids.
- This is the first report of Scenedesmus spp. infection in any fish.
- Algae located under scales and within the dermis, coupled with granulomatous response, may explain treatment failure.