Nematodes of the genus Eustrongylides can infect many fish species inhabiting freshwater and marine ecosystems worldwide. All species of these parasites described in fish have indirect life cycles and fish are the second intermediate hosts or paratenic hosts, and the prey of fish-eating birds, as the definite hosts. Eustronoglydes are typically coiled, smooth, and relatively long worms that are red in colour due to the presence of haemoglobin. A large number of parasite larvae in fish can cause severe forms of the disease, affecting the fertility of some species and increasing mortality. The best method for diagnosis of fish eustrongylidosis is necropsy of several affected individuals, and identification of the parasite by their morphological characteristics and position in the fish. It is necessary to exclude other fish parasites, including flatworms, segmented tapeworms, monogenean and digenean flukes and acanthocephali. To prevent eustrongylidosis in fish, the parasite life cycle must be interrupted in one of the developing stages, which requires removing any of the intermediate or final hosts. For farmed fish, pond sanitation is important in preventing fish infection. Fish eustrongylides have been identified as causative agents of infection in humans as accidental hosts, and although a small number of clinical cases have been described, eustrongylidosis is a recognized zoonosis. To prevent human infection, it is recommended to avoid consuming of raw fish and raw fish products. An effective method of killing parasites is freezing and heat treatments, under well-defined conditions.

Oblići roda Eustrongylides se nalaze širom svijeta u brojnih riba slatkovodnih i morskih ekosustava. Sve vrste ovih u riba opisanih parazita imaju neizravni razvojni ciklus te su ribe drugi međudomaćin ili paratenični nositelj i plijen ribojednih ptica koje su konačni domaćini. Eustrongilidi su oblikom okrugli, glatki, relativno dugački crvi zbog prisustva hemoglobina crvene boje. Veći broj ličinki parazita u ribi može izazvati teške oblike bolesti, utjecati kod nekih vrsta na plodnost i povećati smrtnost. Za dijagnozu eustrongilidoze sigurna metoda je razudba male grupe zaraženih riba te mjesta nalaza i karakteristike parazita u ribi. Potrebno je isključiti druge parazite riba - crve plošnjake, segmentirane trakavice, jednorodne i dvorodne metilje te akantocefale. Za prevenciju eustrongilidoze u riba potrebno je u nekom od razvojnih stadija prekinuti životni ciklus parazita za što je potrebno ukloniti bilo kojeg međudomaćina ili konačne domaćine. Za uzgajane ribe, sanitacija ribnjaka omogućava prevenciju zaraze ribe od ovih parazita. Eustrongilidi riba su identificirani kao uzročnici infekcije ljudi kao slučajnih domaćina te iako je opisan mali broj kliničkih slučajeva, eustongilidoza je priznata zoonoza. Da bi se spriječila infekcija ljudi preporuka je izbjegavati konzumiranje sirove ribe i sirovih ribljih proizvoda. Učinkovita metoda ubijanja parazita je temeljita termička obrada.