Fish of the family Syngnathidae include seahorses, pipefish and seadragons. Many of these species are currently listed as threatened or endangered under Appendix II of the Convention on International Trade of Endangered Species (CITES). Research related to syngnathid disease is slowly emerging. However, these fish still provide a serious challenge for aquarists, and in the wild, overexploitation of syngnathids continues. It is therefore critical that we understand disease related to husbandry, as captive rearing of syngnathids may be an invaluable tool in relieving pressures on wild populations. In our diagnostic research, we chose to conduct a ten year retrospective study of syngnathid diseases observed at the Toronto Zoo (1998-2008). This review comprises 118 cases. The major reoccurring problems are the following: bacterial and/or protozoal dermatitis, suspected nutritional myopathy, mycobacteriosis, gas bubble disease, cryptosporidiosis and several neoplasms. The bacterial dermatitis was the most common diagnosis, occurring in over thirty percent of cases. This dermatitis appears to be associated with the clinical condition 'redtail'. Further investigation of the bacterial dermatitis, which is a significant clinical concern, was therefore undertaken. We hypothesize that the filamentous bacterium seen in the erosive/ulcerative dermatitis lesions by light microscopy are associated with the development of 'redtail'. This will be investigated in detail by bacterial isolation, biochemical tests, immunohistochemistry and polymerase chain reaction.