Gut contents of sand goby Pomatoschistus minutus showed higher C and N isotope values than the food before consumption. This enrichment was more pronounced in the hindgut than in the foregut, probably because of preferential assimilation of 12 C and 14 N along the gastro‐intestinal tract. The results indicated that the shift towards higher values in the alimentary canal occurs in the first 2 h after feeding.

An acoustic deterrent system producing 20–600 Hz sound was used to repel estuarine fishes away from a power station cooling water inlet. During sound emission, total fish impingement decreased by 60%. The avoidance response varied among species from no effect to highly efficient deflection. Lampetra fluviatilis and Pleuronectiformes were less affected by the sound system while the deflection of clupeoid species was particularl...

Two living specimens of the Atlantic croaker Micropogonias undulatus have been caught during recent years in Belgian waters (Southern Bight of the North Sea): one in August 1998 as a by‐catch of the commercial shrimp fishery in coastal waters, another in October 2001 on a tidal flat in the brackish part of the Scheldt Estuary. These represent the first records of this north‐west Atlantic species in European waters, and their o...

The inherent ability of the carp Cyprinus carpio gut to absorb intact salmon gonadotropin hormone‐releasing hormone analogue (sGnRH‐a)+Pimozide (Pim), without loss of their bioactivity is very limited. Artificial intestinal absorption enhancement boosted sGnRH‐a and Pim induced GtH II release and milt production significantly. The intraperitoneal route of administration was more effective than the oral one. A potential applica...

The optimal ratio of spermatozoa : egg (15 000 : 1) for artificial insemination of African catfish Clarias gariepinus gave fertilization and hatching rates of 80 and 67%, respectively. Below a sperm : ova of 3000 : 1 fertilization success decreased significantly. Excessive sperm (>15 000 : 1) partly inhibited fertilization success. Sperm motility was decreased significantly by 0·001 mg 1 −1 Hg 2+ as HgCl 2 , but its effect on...

Fish living in the tidal fresh and brackish water reaches of the Zeeschelde Estuary were studied in samples collected from the cooling‐water inlets of three power stations. Between July 1994 and June 1995, 42 different species were recorded including 26 marine migrants, 14 freshwater species and two diadromous species. Species number as well as fish abundance were correlated significantly with salinity and oxygen concentration...

Mass mortalities of the European sea bass, Dicentrarchus labrax (L.), occurred in different ongrowing units in Greece. A presumptive diagnosis of viral nervous necrosis (VNN) was made on the basis of the light microscopic observations of a vacuolating encephalopathy and retinopathy. Positive peroxidase reaction with VNN antiserum confirmed nodavirus as the causative agent. Usually recorded in larvae and juvenile stages of diff...

The feeding ecology of four species of Xenotilapia (Teleostei, Cichlidae) from Lake Tanganyika was investigated by examining their intestine contents in three different habitats from two 24‐h catch cycles. The fish were caught in a sandy bay 4 km north‐west of Bujumbura (Burundi) during the dry season, from August until October 1993. Three different habitats were sampled: an area 600 m offshore at a depth of 15 m, a littoral z...