The aim of the presented study was testing the efficacy of an herbal concoction in goldfish (Carassius auratus) experimentally infected with Aeromonas hydrophila. After an intramuscular injection of the pathogen, the scales sloughed off on the site of the injection, with an appearance of a muscular haemorrhagic protuberance, which progressed into an extensive ulcerative dermatitis associated with focal haemorrhage, oedema, and dermal necrosis exposing the underlying muscle. The progression of the disease affected organs in the following order: muscle, gills, liver, and finally the heart. The dip treatment with the 1% herbal concoction for 5 min daily restored the macro- and microscopical structure of the altered primary gill lamellae, liver, heart, and muscles. The recovery changes were described.
Experiments were conducted to document behavioural responses of koi carp, Cyprinus carpio L., and goldfish, Carassius auratus (L.) to monoculture and polyculture conditions in aquaria. Two parallel experiments, otherwise involving similar experimental protocols, were carried out with two batches of fish, fed with live tubifex worm (first batch) and live zooplankton (second batch). Each of the trials, randomized with respect to treatment, yielded data on aggressive encounters (chases, nips), both in presence and absence of food. The two species exhibited considerable variation in the extent and type of aggression displayed, koi carp being the more aggressive species. Frequency of attack increased in the presence of food. The impact of aggressive behaviour of koi carp was conspicuous by the increased level of attack on goldfish in polyculture trials in both experimental batches.