Abstract
Granulomatous gastritis has been described in both Old World and New World cichlids with several possible etiologies including Cryptobia
iubilans infestation and improper diet. However, an increasing number of reports suggest that protozoans are the primary etiologic agents. This report
summarizes one case involving a discus breeding operation in which juvenile discus were affected most dramatically.
A cichlid breeder experienced morbidity and mortality in his discus population over the course of several weeks. All life stages were
affected. More mature and larger fish experienced morbidity but minimal mortality. Breeder discus turned dark, had increased mucus production, and became
laterally recumbent for one or more weeks before recovering. Fish two months or older also were affected with limited mortality. However, two-to four-week-old
fish experienced high mortality, up to 70% or more.
Wet mounts and histological sections of affected juveniles revealed several gastrointestinal parasites. Minimal numbers of nematodes and
flagellated protozoans, presumably Spironucleus sp. or Hexamita sp. were noted in the intestine. Great numbers of another species of flagellated
protozoan were found in many of the stomachs examined as well as within the intestinal tract. The primary pathologic lesion seen was granulomatous gastritis, and
in some sections of submucosa, protozoans were seen within vacuolated cells, presumably macrophages. These gastric flagellates closely resembled, in both
appearance and associated pathology, Cryptobia iubilans, but electron microscopic verification is pending. Microbiologic culture of kidney and brain were
negative. During the outbreak, several chemotherapeutants were attempted in both bath and oral treatments with limited success. At least two other cases of
presumptive Cryptobiosis have been seen in discus from different breeding operations throughout the United States. Attempts to culture the organisms in
vitro are ongoing, as are chemotherapeutic field trials.
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