The appearance of artificial, seminatural and modified natural fishing baits can be dismatched with their taste. In the laboratory experiments described below, we have tested the responses of model fish to baits of this kind.

Juvenile induviduals of wild common roach, Rutilus rutilus, tench, Tinca tinca, crucian, Carassius carassius, and home goldfish, Carassus auratus, of about 5,0-5,5 cm standard length, were used in the experiments. Each fish were trained individually to eat seminatural sideswimmers, Gammarus lacustris, of calibrated 6,0-6,1 mm length, within 10 days in order to form an acquired search image, visual and gustatory, in respect of this food. Then modified sideswimmers, with the taste of white worms, Enchytraeus albidus, earthworms, Lumbricus terrestris, molluscs, Unio pictorum, and grey meat-fly larvae, Sarcophaga carnaria, were offered for comparison.

Seminatural sideswimmers were prepared of natural amphipods by soaking them in pure alcohol, within 12 hours, and subsequent rinsing in pure flowing water, within 2 hours. Then soaking prey were placed into the mess of crushed natural amphipods for 12 hours, to return them the (semi)natural taste. In other four cases, soaking amphipods were gustificated for the same 12 hours in the mess of white worms, earthworms, molluscs and grey meat-fly larvae, respectively.

Note, seminatural and modified amphipods had the same pale color.

Fish were trained to eat seminatural amphipods which were offered one by one through the transparent glass tube in the aquarium cover. Fish noticed the sinking amphipod and fell behind it. When the sinking amphipod appeared out of the tube, fish grabbed it, tested some time, spitting and grabbing, and ate or ignored.

After 10 day training, fish usually ate each seminatural amphipod immediately, without test spittings, or after no more than 1-2 spittings. However, when an amphipod with an unfamiliar taste was offered, this picture changed. The number of spittings increased dramatically, up to 12-16 and more during the first familiarization. Fish mostly rejected an unusual amphipod, then returned to it to test again and so on. In general, about 10 days of training were needed in order to return the number of test spittings to the minimum, that is to 0-2 spittings.

No differences were observed between natural amphipods and amphipods with the restored taste.

... Read more »