Goldfish Fry Research Articles

Growth Responses and Survival of the Goldfish, <i>Carassius auratus </i>(Cyprinidae) Fry Reared on <i>Moina</i> (Cladocera) and <i>Cyclops</i> (Copepoda)

Five sets of 20-day old goldfish fry, Carassius auratus with average weights of 0.167 ± 0.003 g were reared for eight weeks in plastic bowls for growth and survival studies. One set (labelled MN) was fed Moina and Cyclops. A second set (labelled FM) was fed fishmeal, and a third set (labelled AF) was fed a 45% protein artificial feed. The fourth and fifth sets were fed mixtures of Moina/Cyclops with the fishmeal (MFM) and the artificial feed (MAF). Survival was 60% in the fry fed fishmeal (FM) alone but 100% in all the other groups. Specific growth rate (SGR) and mean weight gain was not significantly different (P > 0.05) in fry fed Moina/Cyclops alone (MN) or in combination with fishmeal (MFM) and artificial feed (MAF). They were, however, significantly different (P < 0.05) from those of fry fed fishmeal (FM) and artificial feed (AF) The best mean weight gain of 2.796 ± 0.006 g (over 1600%) was recorded in the fry fed Moina/Cyclops alone. Weekly percentage weight gain also followed a similar trend. Moina/Cyclops are recommended to aquaculturists for goldfish fry rearing instead of artificial feeds, fishmeal or the expensive Artemia franciscana. It is also recommended that this zooplankton be augmented in later stages with fishmeal to enhance fry growth and survival. Key words: Moina, Cyclops, Goldfish, Carassius auratus, Larval fish nutrition. Journal of Aquatic Sciences Vol.18(1) 2003: 43-46

Effect of density on survival and growth of cyprinid fish fry

One of the bottlenecks in Israel's cold water ornamental fish industry is the large loss of fish during the post-larval stage. As a first step towards increasing survival rates, the optimal stocking density in earthen ponds for fry of each species should be determined. The results of five consecutive experiments with fry of goldfish (Carassius auratus), common carp and koi (respectively, edible and ornamental morphotypes of Cyprinus carpio) are presented here. The experiments were run in 18 cages of 1 m3 and 0.8 mm mesh size placed in a 0.02 ha earthen pond, stocked at 50,100 and 200 fry per cage. The variables analyzed were growth rate, harvesting weight, biomass and survival. Equations to estimate growth rates under different conditions are given. The three fish types present different growth rates and survival patterns in relation to stocking density and season, which lead to different management implications. Koi can be stocked up to 2 million fry per ha without showing negative density effects. Goldfish should be stocked at low density (500,000–1 million fry per ha) in spring and at higher rate (2 million fry per ha) in summer. Common carp stocking density should be adjusted to obtain the required fish size at harvest.

Smooth endoplasmic reticulum in fish Mauthner cells at different functional states

The ultrastructure of Mauthner cells of goldfish fry and adult xenotoca in intact state and after prolonged natural stimulation has been studied qualitatively and quantitatively. Additionally, Mauthner cells of intact adult goldfish and adult rotan Percottus glehni were investigated. In all adult fish the dendroplasm of the two major dendrites was shown to contain a regular network of smooth endoplasmic reticulum, with cisterns and tubules arranged transversally to the dendrite stem. In the Mauthner cells of intact goldfish fry, the reticulum was not clearly expressed, the transversal cisterns occurred occasionally. After stimulation, however, it became more developed probably due to proliferation of additional transversal cisterns. The periodicity of transversally oriented cisterns in the dendrites of Mauthner cells in each fish species studied was nearly the same. However, the number of transversal cisterns per unit of dendrite length, and the total length of cisterns and tubules per unit of cross-section area varied both within and among the species. These parameters increased after stimulation. It is suggested that the proliferation of the transversal cisterns in the endoplasmic reticulum and the extent of their development depend on the functional state of the afferent synapses and the plasticity of the smooth reticulum reflects the involvement of postsynaptic mechanisms in regulation of Mauthner cell stability presumably via the regulation of calcium homeostasis under varying conditions of functioning.

Ultrastructure of Mauthner cells in fish adapted to long-duration vestibular stimulation and the effect of ethanol.

Adaptation or resistance of fish Mauthner cells (M-cells) to long duration (2 h) vestibular stimulation (LDS)was produced by daily brief and gradually increasing vestibular stimulation (training). The LDS resistance was accompanied by an increase in the number of desmosome-like junctions in the afferent axosomatic synapses. F-actin, the main component of desmosome-like contacts, has been suggested to be responsible for the increased resistance of M-cells to LDS. The purpose of the present study was to investigate the capacity of M-cells to adapt to LDS under the influence of ethanol, which alters the content of F-actin in cells. The experiments were carried out in goldfish fry. Vestibular stimulation (training and LDS) was performed in special drums that were rotated in two planes. The training time was increased from 1 min on day 1 to 30 min on day 30. For ethanol exposure, fish were immersed daily in a 2% ethanol solution for 20 min. To assess the level of resistance to LDS, motor activity indicating the functional state of M-cells was evaluated before and after LDS. The results show that exposure to ethanol reduces the resistance to LDS in both untrained and trained fish. Electron microscopic data demonstrated some structural changes in the synaptic endings located on M-cell soma in ethanol-exposed fish. Wrapping of boutons by cytoplasmic out- growths and myelin- like structures was observed. Morphometric analysis revealed that exposure to ethanol without training decreases the number of desmosome-like contacts, probably due to ethanol-induced depolymerization of cytoskeletal actin. Ethanol exposure also partly suppressed the increase in the number of desmosome-like contacts that occurs as a result of training. In ethanol-treated trained fish, however, a concomitant increase in the length of desmosome-like contacts was observed. As training alone leads to the formation of additional desmosome-like contacts of standard length, it is possible that although a sufficient amount of such structures cannot be formed in the M-cells of ethanol-exposed trained fish, the existing contacts can be elongated. Thus, possibly changes of the actin state are involved in the adaptation of M-cells to LDS.

Studies On The Experimental Mode Of Infections Of Clonorchis Sinensis: II. Experimental Infection Of Clonorchis Sinensis Cercaria To Fry Of Fresh Water Fishes

Cercariae of Clonorchis sinensis were attempted to penetrate into various fry of fresh water fishes in order to examine the conditions of infection and the further development in the fish. The following conclusions were made. 1. Cercariae of C. sinensis penetrated into the muscle of the fry of Pseudorasbora parva were found to be able to develop. 2. Cercariae penetrated into the fry of Pseudorasbora parva migrated into the organs of the fry to kill their host. 3. From each dead individual of P. parva, more than 10 larvae of C. sinensis could be discovered. 4. Cercariae attached on the Cyprinus carpio, Carassius and gold fish were almost killed before penetration into the body and even one or two cercariae penetrated were also killed as time passed. 5. Cercariae of C. sinensis infected on the fry of Cyprinus Carpio, Carassius auratus and gold fish could not survive more than 60 days. 6. Cercariae penetrated into Cyprinus carpio and Carassius auratus could not develop into complete metacercariae even after 3O days. 7. Cercariae of Clonorchis sinensis penetrated into the fry of Aplocheilus latipes were killed within 10 hours and the cercariae attached on the caudal fin were destroyed in 2 hours. 8. It was found that no cercariae of Clonorchis sinensis could penetrate into the body of the fry of Misgurnus anguillicaudatus.

種苗増産に關する研究(第1報)和金孵化兒の餌付開始時期が成長減粍及び褪色等に及ぼす影響(豫報)

The Gold-fish fries which were hatched at the same time, from the same parent fish, grow up in different grade. It seems to be not only due to the heredity but also the fact whether they were given enough feed soon after they were hatched. Four groups were put into experiment; that is, the one was fed immediately after they were hatched, and the other threes were begun to feed on the fifth day, on the tenth and on the fifteenth after they were hatched respectively. They were fed in the pots for 153 days and their growth, survival and decolaration of the body were examined. The result is as follows. 1. The fluctuation of growth of the newly hatched fry of Gold-fish seems to be increased, when the beginning time of artificial feeding is delayed. In consequence, the appearance of special larged-sized or small-sized fry might be caused more by the different power of individuals aquired under the enviroment of their habitat rather than that of their own heredity. 2. The more the beginning time of artificial feeding is delayed, the less (in number) the fries survive and the more the phenomenon of decoloration of their body is slowly presented.