Gonad development in 4‐year‐old triploid and diploid ornamental koi, a variant of Common Carp Cyprinus carpio, from corresponding heat‐shocked and control progenies was investigated. Diploid males were normally mature. Triploid males from heat‐shocked progeny demonstrated development of testes typical for triploid fish; triploid males did not release sperm and their testes had a pinkish color and were significantly reduced in size. Diploid females were normally mature and their gonadosomatic indices (GSIs) varied from 7.5% to 30.7% and the mean value was 21.3%. Triploid females had unexpectedly well‐developed ovaries, which were filled with fully grown oocytes; their GSIs varied from 4.2% to 30.1% and the the mean value was 17.0%. Four triploid koi females released large quantities (from 260,000 to 394,500 eggs per female) of ovulated eggs after hormonal injection. Eggs from triploid females were fertilized with sperm from normal diploid koi males. Mass mortality of hatched larvae occurred at the swim‐up stage, but about 32,000 swim‐up larvae were obtained and stocked for further rearing. A total of 248 juveniles (or less than 1% from the number of stocked larvae) were collected from outdoor tanks. Ploidy analysis of juveniles (n = 110) showed that most of them were aneuploid with ploidy ranging from 2.3n to 2.9n with a mean value of 2.6n; two juveniles were diploid (2n). This shows that triploid koi females produced aneuploid eggs with a ploidy range from haploid to diploid level with the modal ploidy level around 1.5n, similar to the production of aneuploid spermatozoa observed earlier for triploid males in fish.

Atrazine is a commonly used herbicide that has previously been implicated as an endocrine-disrupting compound. Previous studies have shown that estrogenic endocrine-disrupting compounds affect the development of the heart, cartilage, and bone in zebrafish ( Danio rerio). To determine whether atrazine has effects similar to other endocrine disruptors, zebrafish embryos were treated with a range of atrazine concentrations. Atrazine treatment at a low concentration of 0.1 µM resulted in significant differences in craniofacial cartilage elements, while concentrations ≥1 µM led to decreased survival and increased heart rates. Fish treated with ≥1 µM atrazine also developed with delayed vertebrae mineralization. Higher concentrations of atrazine caused gross craniofacial defects and decreased hatching rates. Further studies into the molecular pathways disrupted in these developmental processes could shed light on a link between endocrine-disrupting compounds and developmental abnormalities.

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The purpose of this study was to investigate the reproductive ability of second generation (F 2 ) koi (Cyprinus carpio L.) 9 goldfish (Carassius auratus L.) hybrids. Only

Four cross combinations of different YY male and female Nile Tilapia Oreochromis niloticus strains were evaluated for growth, sex, and color segregation. Red color parental strains included blotched phenotypes. The Genetically Improved Farmed Tilapia (GIFT) was the only dark (wild‐type) color parental strain. Fish of the same age and cross were stocked in three replicate tanks for four crosses in one recirculating system for 167 days. Data recorded included feed consumed, body weight, total length, color, sex, and fillet weight. YY males crossed with GIFT females (Cross 2) exhibited superior growth that was significantly different (p < .05) to other three crosses. Male proportions were 79–100%. Only YY males crossed with the LSA female strain (Cross 4) yielded 100% males, but, Cross 4's productivity was inferior to that of Cross 2. Body weight advantage of males over females was 28.7–84.2%. Color segregation indicated that red color trait in Nile Tilapia is autosomal dominant, and black patch coverage was variable. This study showed that different parental strain combinations clearly impact productivity traits, and that YY male technology combined with crossbreeding provide the opportunity for genetic improvement and development of commercially beneficial superior traits in Nile Tilapia.