Common fish diseases and parasites affecting wild and farmed Tilapia and catfish in Central and Western Uganda

Intensification of aquaculture production in Uganda is likely to result into disease out-breaks leading to economic losses to commercial fish farms and associated natural aquatic ecosystems. This survey assessed health profiles of selected commercial fish farms and adjacent natural aquatic ecosystemsto identify fish diseases and parasites affecting Nile tilapia (Oreochroms niloticus) and African catfish (Clarias gariepinus) in aquaculture systems in Uganda. Fish farms encounter disease out-breaks that cause low survival rates (0 - 30%), especially catfish hatcheries. Health management issues are not well understood by fish farmers, with some unable to detect diseased fish. Current control strategies to control aquatic pathogens include use of chemo- therapeutants and antibiotics. Bacterial pathogens isolated included Flavobacterium columnare, Aeromonas sp., Edwardsiella sp., Psuedomonus sp., Steptococcus sp., Staphylococcus sp., Proteus sp., and Vibrio sp. A high occurrence of Flavobacterium columnare exists in both asymptomatic and symptomatic fish was observed. Parasites included protozoans (Ichthyopthirius multiphilis, Trichodina sp. and Icthyobodo sp.) and trematodes (Cleidodiscus sp. and Gyrodactylus sp.). Diagnosis and control of diseases and parasites in aquaculture production systems requires adoption of a regional comprehensive biosecurity strategy: the East African (EAC) region unto which this study directly contributes

Monogeneans (Dactylogyridae) parasitizing gills ofSalminus hilarii from a Neotropical reservoir, Brazil

With the aim of creating an inventory of the metazoan gill parasites of Salminus hilarii in the Taquari River, state of Sao Paulo, Brazil, five species of monogeneans (Anacanthorus contortus, A. bicuspidatus, Annulotrematoides parisellei, Jainus iocensis and Tereancistrum arcuatus) are reported the first time for this host. A total of 28 fish were sampled quarterly between April 2011 and January 2012, with 10 hosts in a lentic ecosystem and 18 in a lotic ecosystem. Quantitative ecological descriptors (prevalence, intensity of infestation and abundance) were calculated for the purpose to comparing the two ecosystems sampled (lentic and lotic ecosystems). However, no quantitative difference between the lentic and lotic ecosystems was observed. The present study has made available a checklist for species of the genus Anacanthorus and their hosts and geographical distribution in the Neotropical region up to the present time.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ Estadual Paulista, UNESP, Inst Biociencias, Lab Parasitol Anim Silvestres LAPAS,Dept Parasito, BR-18618970 Botucatu, SP, BrazilUniv Estadual Paulista, UNESP, Inst Biociencias, Lab Biol & Ecol Peixes,Dept Morfol, BR-18618970 Botucatu, SP, BrazilUniv Estadual Paulista, UNESP, Inst Biociencias, Lab Parasitol Anim Silvestres LAPAS,Dept Parasito, BR-18618970 Botucatu, SP, BrazilUniv Estadual Paulista, UNESP, Inst Biociencias, Lab Biol & Ecol Peixes,Dept Morfol, BR-18618970 Botucatu, SP, BrazilFAPESP: 11/22603-3CAPES: AUX-PE-PNPD 3005/201

Prevalence and pathology of protozoan and monogenean parasites from fry and fingerlings of cultured Clarias gariepinus (Burchell, 1882) in Uganda

Aquaculture is considered the best option for the dwindling capture fisheriesin Uganda. Among the economically important aquaculture fish specieswith very successful breeding technologies is African catfish, Clariasgariepinus. However, farmers are constraint with massive fry and fingerlingmortalities, especially in intensive culture system. Despite the fact thatparasites and diseases are reckoned to be the causes of these mortalities,little has been done to authenticate this claim in Uganda. Therefore thisstudy investigated the cause of mortalities with the aim of establishinginformation on the prevalence and pathology of Protozoa and Monogeneaparasites occurring on C. gariepinus. Using routine parasitological andhistological techniques, a total of 334 fry and fingerlings of cultured C.gariepinus from three hatcheries were examined for parasite infestations.Five ectoparasites and one endoparasite species were recorded. Of these, theprotozoan Trichodina sp. and the monogenean Gyrodactylus sp. were thedominant parasites. The major routes of entry of parasites into the hatcherieswere through surface water supply and possibly via the semi aquaticorganisms like amphibians. During initial stages of infection, the prevalence,mean intensity and mean abundance of these parasites increased with fishage. At the later stage, Trichodina sp. declined probably due to hostresistance and competition for space with Gyrodactylus sp. Trichodina spappeared less susceptible to the 40ml/l formalin treatment thanGyrodactylus sp. Major pathological changes observed were oedema andhyperplasia in the gills, infiltration of melanomacrophage centers into theskin epidermis and mild epidermal cell hypertrophy of parasitized fish.Hyperplasia and oedema of gill and subsequent gill fusion seem to haveinterrupted respiration and hence caused death of the host. Concomitantoccurrence of Trichodina sp. and Gyrodactylus sp. aggravated pathologicaleffects on fish thus increasing mortality. Epistylis sp., Apiosoma sp. andTrichophrya sp. were considered less pathogenic. The results werediscussed in relation to parasite occurrence and parasite induced fishmortalities

Infection dynamics of Cichlidogyrus tilapiae and C. sclerosus (Monogenea, Ancyrocephalinae) in Nile tilapia (Oreochromis niloticus L.) from Uganda.

The infection dynamics of the gill monogeneans Cichlidogyrus tilapiae and C. sclerosus on Oreochromis niloticus with respect to habitat type (reservoir, stream, ponds and cages), host sex, size and seasons was determined between January and November 2008. During the study period, 45.2% of the 650 fish examined were infected with Cichlidogyrus spp. The infected hosts harboured an average of 8.6 \ub1 3.4 parasites/fish. Across habitat types, the proportion of infected fish was not statistically different. In contrast, the number of parasites recorded on infected fish from different habitat types differed significantly. The highest parasite number was recorded in reservoir-dwelling fish and lowest in stream-dwelling hosts. Concerning sex, more female O. niloticus were infected and harboured a high number of parasites than male and sexually undifferentiated fish. A weak negative relationship was found between rainfall and monthly parasite infections. However, a higher number of parasites and proportion of infected hosts were found during dry than in wet seasons, except in ponds. Results of this study show that differential exposure due to changes in fish behaviour associated with habitat modification and sex may account for the infection difference across the sampled sites. Meanwhile, rainfall and the associated hydrological events are important factors regulating monogenean infections in tropical aquatic environments. The continuous presence of Cichlidogyrus spp. in fish provides evidence of possible parasite outbreaks, indicating the application of biosecurity measures as crucial for the success of intensive fish farming

Common fish diseases and parasites affecting wild and farmed tilapia and catfish in central and western Uganda

Intensification of aquaculture production in Uganda is likely to result into disease out-breaks leading to economic losses to commercial fish farms and associated natural aquatic ecosystems.This survey assessed health profiles of selected commercial fish farms and adjacent natural aquatic ecosystemsto identify fish diseases and parasites affecting Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) in aquaculture systems in Uganda. Fish farmsencounter disease out-breaks that cause low survival rates (0 - 30%), especially catfish hatcheries.Health management issues are not well understood by fish farmers, with some unable to detect diseased fish. Current control strategies to control aquatic pathogens include use of chemotherapeutants and antibiotics. Bacterial pathogens isolated included Flavobacterium columnare,Aeromonas sp., Edwardsiella sp., Psuedomonus sp., Steptococcus sp., Staphylococcus sp., Proteus sp.,and Vibrio sp. A high occurrence of Flavobacterium columnare exists in both asymptomatic andsymptomatic fish was observed. Parasites included protozoans (Ichthyopthirius multiphilis,Trichodina sp. and Icthyobodo sp.) and trematodes (Cleidodiscus sp. and Gyrodactylus sp.). Diagnosisand control of diseases and parasites in aquaculture production systems requires adoption of a regional comprehensive biosecurity strategy: the East African (EAC) region unto which this study directly contributes