Almost 200 years have passed since the first description of a marine fish parasite from South Africa. It is therefore an opportune time to look back, take stock of and reflect on the history of discovery within this field and, based on what we know, propose the future direction for research. The aim of this paper is hence to provide some background information on the growth in our knowledge and understanding of the major groups of marine fish parasites and to give an account of how pioneers, such as Barnard, Stebbing, Fantham and Kensley, led the age of discovery and exploration in marine fish parasitology in South Africa. The paper also presents a brief overview of the contributions made by internationally acclaimed parasitologists, such as Rodney Bray and Angela Davies, to our knowledge of marine fish parasites from this region and also to acknowledge the role played by the South African parasitologists, especially over the past 30 years. A rich base of fundamental knowledge is available in South Africa and this research field continues to grow. The prognosis for the future of marine parasitology in South Africa is good; however, as we continue to acquire and record new information about species, it is proposed that future research should be more focused on the lesser studied groups, such as monogeneans, protists and Myxozoa, as these have received uneven attention to date. In addition, it is proposed that the scope of research on marine fish parasitology be broadened to include ecological and applied aspects, using modern techniques.

The paper presents an overview of the history of aquatic parasitology of freshwater fish in southern Africa. Aquatic parasitology has become a very popular field of specialisation in South Africa and is currently practised by a number of individual research groups at different universities. So far most research deals with parasites of wild fish rather than pathogens of aquaculture. It is written as a narrative and summarises the aquatic parasitology research mostly on fish parasites carried out at the universities of Cape Town, Free State, Johannesburg, Limpopo, Pretoria, North West and Sefako Makgatho Health Sciences. It is not intended to be a review in the classical way because it deals with parasites ranging from Protozoa to Arthropoda.

Globally small mammals are important hosts of ectoparasite vectors of pathogens of medical, veterinary and economic importance. Insectivores are currently understudied as hosts of pathogen vectors. However, data are needed on the diversity of such vectors before we can investigate the underlying factors affecting ectoparasite distribution. Abiotic (e.g. temperature and rainfall) and biotic (e.g. host sex) factors have been identified as the main determinants of host—parasite interactions. The present study describes the ectoparasite community of insectivorous eastern rock sengis (Elephantulus myurus) in a nature reserve in the Gauteng province, South Africa, and how it varies with season and host sex. A total of 81 sengis were examined for the presence of ticks, mites, fleas and lice between April 2010 and April 2011. The ectoparasite assemblage comprised 11 groups of tick species, a single mite family, one louse and two flea species, with ticks and mites being the most numerous ectoparasites recovered. The prevalence and/or abundance of two commonly collected ticks (Ixodes spp. and Rhipicephalus warburtoni/arnoldi) and chigger varied with season. In addition, female-biased tick burdens were apparent for one ectoparasite species possibly due to reproductive investment. The mechanisms causing the observed patterns should be addressed in future studies.

This study investigated the seasonal dynamics and occurrence of dactylogyrids on the gills of three cyprinids at Nwanedi—Luphephe dams from January to October 2008. The hosts, Labeobarbus marequensis (n = 53), Barbus trimaculatus (n = 63) and Barbus radiatus (n = 46), were collected using gill nets, cast nets, electrofishing gear and seine nets. A total of three Dactylogyrus species were found. Dactylogyrus spinicirrus was collected from all hosts, whereas Dactylogyrus afrolongicornis alberti and Dactylogyrus afrolongicornis afrolongicornis were collected from B. trimaculatus. Although D. spinicirrus was the most prevalent parasite on all three hosts, its mean intensity per host was found to be less than 10 individuals per host. Dactylogyrus afrolongicornis alberti and D. afrolongicornis afrolongicornis were less prevalent on the hosts, occurring in less than 50% of all hosts sampled, with a mean intensity of less than five individuals per host. The study showed that the intensity of D. spinicirrus infestation was influenced by season. Its occurrence displayed seasonal fluctuations with prevalence and mean intensity increasing with an increase in water temperatures. Other predictors of infestation such as fish sex and length did not have a significant influence on the prevalence and intensity of D. spinicirrus. Furthermore, parasite burdens did not have an effect on the condition of the host.

There are 21 species in the genus Kroyeria of which nine have been reported from hosts caught off South Africa. Host—parasite associations were reported for K. dispar, K. papillipes and K. sphyrnae. Kroyeria specimens were collected from the gill filaments of elasmobranch hosts, fixed and preserved in 70% ethanol and the prevalence, mean intensity and mean abundance calculated. Kroyeria lineata from Mustelus palumbes constitutes a new host and geographical record, K. rhophemophaga from Galeorhinus galeus a new geographical record and K. carchariaeglauci from Carcharhinus amboinensis an additional new host record. Except for K. dispar, Kroyeria species generally display low parasite loads on their hosts. Prevalence varied between 11.8% (Cl: 1.5–36.4%) and 94.4% (Cl: 86.4–98.5%). Mean intensity and mean abundance values ranged from four to 72.8 (SE 11.1) individuals per infected host and from 0.7 (SE 0.5) to 65.7 (SE 10.5) individuals per examined host, respectively. All Kroyeria species examined display an aggregated distribution pattern. This study confirms previous suggestions that Kroyeria species are generally host specific, with only a few species found on multiple hosts.

A total of 1 847 fishes (16 species) from 14 reservoirs in northern and north-eastern regions of South Africa were collected and examined for larval Contracaecum spp. between 2005 and 2013. This study, the first to examine several potential second intermediate hosts, found Clarias gariepinus, Coptodon rendalli, Cyprinus carpio, Hydrocynus vittatus, Labeobarbus marequensis, Marcusenius macrolepidotus, Micropterus salmoides, Oreochromis mossambicus and Schilbe intermedius infected with the third-stage larvae. Coptodon rendalli, Marcusenius macrolepidotus and Micropterus salmoides are new host records for South Africa. A generalised linear model identified locality as the main factor affecting parasite burden.

Described species of the polystomatid flatworm genus Eupolystoma are only known from Africa and India. A survey conducted in January 1994 in Namibia revealed a previously unknown species from the urinary bladder of Hoesch's pygmy toad Poyntonophrynus hoeschi. Toads were screened from eight different localities within their known distribution. The toads found to be infected were from three localities, namely Mariental, Outjo and Kamanjab in Namibia. Morphologically, this polystome is distinguised from the other known species by a combination of characteristics including the size of the parasite, number of genital spines, and the size and shape of the marginal hooklets. Eupolystoma namibiensis n. sp. is the first polystome to be described from Namibia.

Three species of Mothocya are reported from the east coast of southern Africa: Mothocya plagulophora (Haller, 1880) from Maputo, Mozambique, from the gills of Hemiramphus far (Forsskål, 1775); Mothocya renardi (Bleeker, 1857) from diverse localities in South Africa and Mozambique, from the hosts Strongylura leiura (Bleeker, 1850) and Tylosurus choram (Rüppell, 1837); and Mothocya affinis sp. nov. from Sodwana Bay, South Africa, from the gills of Hyporamphus affinis (Günther, 1866). Mothocya affinis sp. nov. is characterised by relatively small size (maximum 16 mm); large, wide coxae on pereonite 7 that overlap the pleon; uropods that do not extend past the pleotelson posterior margin; produced anterolateral margins on pereonite 1; and a twisted pleon and pleotelson. Mothocya katoi Nunomura, 1992 and Mothocya toyamaensis Nunomura, 1993 are both transferred to the genus Ceratothoa, with M. katoi being placed into junior synonymy with Ceratothoa guttata (Richardson, 1910). Irona ogcocephalus Avdeev & Avdeev, 1974 and I. callionymus Avdeev & Avdeev, 1974 are both transferred to Elthusa, and Irona trillesi Rokicki, 1986 is synonymised with Mothocya longicopa Bruce, 1986. A key to the south-western Indian Ocean species of Mothocya is given, and a table summarising recent and new nomenclatural acts in the genus is provided.

To date, only a single species of Hemolivia, Hemolivia mauritanica (Sergent & Sergent, 1904), has been described from African terrestrial tortoises. Although various haemogregarines have been described from southern African terrapins and tortoises, including species from the genus Haemogregarina and one from the genus Hepatozoon, no species of Hemolivia have been identified previously from southern Africa. Since its morphological redescription, the taxonomic placement of one of these species, Haemogregarina parvula Dias, 1953, was in doubt. Hence, research was undertaken to resolve the true taxonomic position of this haemogregarine. Blood smears from nine wild tortoises of two species, Stigmochelys pardalis and Kinixys zombensis, from South Africa were screened, with the focus on H. parvula. Parasite DNA was extracted from ethanol-preserved blood samples, and fragments of the 18S rDNA gene were amplified by PCR using the primer sets HepF300/HepR900 and 4558/2733. Maximum likelihood and maximum parsimony analyses of 18S rDNA sequences showed that Haemogregarina parvula formed a monophyletic clade with species of Hemolivia within the Hepatozoon clade, not with species of Haemogregarina. It is thus recommended that this haemogregarine be reassigned to the genus Hemolivia, rendering Hemolivia parvula (Dias, 1953) the first species of the genus recorded from southern African tortoises.

The aim of this study was to describe the histopathology of the stomach of the southern mouthbrooder Pseudocrenilabrus philander (Weber, 1897) naturally infected with an endoparasitic monogenoid, Enterogyrus coronatus Pariselle, Lambert and Euzet, 1991. A total of 16 host specimens were collected in February 2014 from Padda Dam (Gauteng province, Johannesburg, 26°17′ S, 27°99′ E). This monogenoid occurred at a prevalence of 56.3%, mean abundance of 2.6 and mean intensity of 4.2. Pieces of stomach tissue with parasites in situ were fixed and processed for routine histological investigations. The anchors and marginal hooks played important roles in the attachment of the parasite to the host. The parasites inserted the sharp curved terminal ends of their anchors into epithelial tissue, while the hooks penetrated superficially and lifted the epithelial tissue. This resulted in a secure attachment and, in most cases, parasites could only be dislodged from the host tissue with some difficulty by using a needle. The histopathological changes caused by the monogenoid on these wild fish were mild and restricted to the vicinity of haptoral attachment. Pleomorphism and mild metaplasia, vacuolation, and mild epithelial hyperplasia occurred in the vicinity of haptoral attachment.

Only a few reports exist on diplostomid metacercariae found in southern African fish and even less information is available on the pathology associated with these infections. During surveys conducted in December 2008 and August 2010, different fish species were collected from the Okavango (Botswana) and Orange—Vaal (South Africa) River Systems. Histological sections were done from intact Tilapia sparrmanii A. Smith, 1840 and Coptodon rendalli (Boulenger, 1896) eyes and the brains of infected Brycinus lateralis (Boulenger, 1900) in order to determine the precise site of infection and the possible pathological effects. It was found that the encapsulated diplostomids from the eyes of the infected haplotilapiine species from the Okavango System caused localised retinal and/or choroid detachments. No pathological effects were observed in the histological sections of the brains of B. lateralis that were infected with diplostomids, except for the presence of red blood or rodlet cells. Tilapia sparrmanii collected from the Orange River were not infected with diplostomids.