Wild spawners of common bream, Abramis brama, were caught in the Kortowskie Lake (north Poland) and transported to a hatchery for artificial spawning. Fish were hormonally induced using GnRH analogue combined with metoclopramide (ovopel). The results of bream reproduction in captivity were compared with fish treated with the combination of hCG and CPE and with control group injected saline. Males from treated groups produced significantly more milt (over 4.3 ml/kg vs. 2.1) of better qualities: spermatozoon concentration (over 9.3 × 10 9 vs. 6.8) and motility (over 85% vs. 62). Females from the control group did not spawn whereas those from hormonally induced groups ovulated: 62% after CPE treatment and 100% after GnRHa treatment. Generally, the fish after ovopel stimulation showed the best hatchery parameters.

Induced spawning in bream, Abramis brama (L), was studied using acetone‐dried common carp pituitary (CP) and bream pituitary (BP) with or without the addition of human chorionic gonadotrophin (hCG). The total dose administered to fish was of 5.0 mg kg−1 BP or 4.0 mg kg−1 CP with or without 2000‐2200 IU hCG kg−1 for females and 2.5 mg kg−1 BP or 2.0 mg kg−1 CP with or without 1000–1100 IU HCG kg−1 for males. In all male treated groups 100% of spermiation was observed: in females the most effective method was a triple injection with hCG and carp pituitary, resulting in 79% of females ovulated (over 68% of eyed eggs). Biological quality of eggs, expressed as a percentage of eyed eggs, was negatively correlated with time elapsing between resolving (final) injection and ovulation. Spawning success, expressed as a value of Se (spawning effectiveness coefficient), was higher in fish treated with triple injection.

Induced spawning in Eurasian perch, Perca fluviatilis L., was studied using human chorionic gonadotrophin (hCG) or acetone-dried common carp pituitary with or without hCG, The dose administered to fish was 5700 IU hCG kg"' or 4,0 mg kg~^ carp pituitary with or without 500-700 IU hCG kg~i for females and 2850 IU hCG kg"' or 2,0 mg kg~' carp pituitary with or without 250-350 IU hCG kg"^ for males. There were no statistically significant differences in quantity of milt in treated and control groups, although the best result was observed when males were treated with a triple injection of hCG and carp pituitary extract, Male spermiating success, expressed as a quantity of milt, was negatively correlated with fish weight. All females treated in this experiment had oocytes at the same division, so time of ovulation was highly synchronous. Spawning success, expressed as a spawning eflectivity coefficient (S^), was highest in fish treated with the triple injection. Spawning methods described in this paper were successful, even though hormones from another order of fish were used.

Induced spawning in perch, Perca fluviatilis L., was studied using follicle stimulating hormone and lutenizing hormone (FSH ϩ LH) with the addition of pimozide or metoclopramide. The doses administered to fish were: 75 IU kg -1 of FSH ϩ LH with 5 or 10 mg kg -1 of pimozide (P) or metoclopramide (M) in females, and 25 IU kg -1 of FSH ϩ LH with 2.5 or 5 mg kg -1 of P or M in males. Hormonal injections in males (except the injection of FSH ϩ LH with 10 mg kg -1 of M) did not influence the quantity of milt obtained. All females treated in this experiment had oocytes at the same stage of nucleus migration, so the time of ovulation was very synchronous, i.e. 16-24 h after injection. The relationship between the quality of the eggs, expressed as a survival to eyed-egg stage, and latency was inverse. Spawning success, expressed as a spawning effectiveness coefficient (S e ), was highest in the fish that had been treated with FSH ϩ LH with a higher dose of M. *Injection from 0.9% NaCl. 132

Induced spawnitig in breatn, Abramis brama (L.), was studied using acetone-dried common carp pituitary (CP) and breatn pituitary (BP) with or without the addition of human chorionic gonadotrophin (hCG). The total dose administered to fish was of 5.0 mg kg"^ BP or 4.0 mg kg"' CP with or without 2000-2200 fU hCG kg-' for females and 2.5 mg kg'' BP or 2.0 mg kg'^ CP with or without 1000-1100 IU HCG kg-' for males.In all male treated groups 100% of spermiation was observed: in females the most effective method was a triple injection with hCG and carp pituitary, resulting in 79% of females ovulated (over 68% of eyed eggs). Biological quality of eggs, expressed as a percentage of eyed eggs, was negatively correlated with time elapsing between resolving (final) injection and ovulation. Spawning success, expressed as a value of Se (spawning effectiveness coefficient), was higher in fish treated with triple Injection.