ẢNH HƯỞNG CỦA HORMONE 17α - METHYLTESTOSTERONE BỔ SUNG VÀO THỨC ĂN LÊN TĂNG TRƯỞNG, CHIỀU DÀI CÁC VÂY, TỶ LỆ SỐNG VÀ TỶ LỆ ĐỰC HÓA CỦA CÁ LIA THIA (Betta splendens Regan, 1910)

Cá lia thia hay cá xiêm đá (Betta splendens) là một loài cá cảnh nước ngọt đặc trưng được nuôi làm cảnh hoặc giải trí thông qua hình thức chọi cá. Nghiên cứu này nhằm tìm ra liều lượng hormone 17α - Methyltestosterone (17α - MT) thích hợp bổ sung vào thức ăn để nâng cao tỷ lệ đực của cá lia thia. Cá bột sau khi hết noãn hoàng cho ăn thức ăn có bổ sung hormone 17α - MT liên tục trong 21 ngày với liều lượng 0, 20, 40 và 60 mg 17α - MT/kg thức ăn, tương ứng với nghiệm thức NT1, NT2, NT3 và NT4. Cá giống được nuôi tiếp tục đến 60 ngày tuổi để xác định tăng trưởng, tỷ lệ sống và tỷ lệ chuyển giới tính trên cá. Kết quả cho thấy tăng trưởng và tỷ lệ sống thì khác biệt không có ý nghĩa thống kê giữa các nghiệm thức (p>0,05). Tỷ lệ đực và chiều dài các vây ở NT3 cao hơn có ý nghĩa thống kê so với NT1 và NT2 (p<0,05), tuy nhiên khác biệt không có ý nghĩa thống kê so với NT4 (p>0,05). Nghiệm thức NT3 đạt tỷ lệ đực hóa (93,8%), hiệu suất đực hóa (84,6%) cao nhất và khác biệt có ý nghĩa thống kê giữa các nghiệm thức (p<0,05). Nghiên cứu này cho thấy bổ sung hormone 17α - MT vào thức ăn với liều lượng 40 mg 17α - MT/kg sẽ làm tăng tỷ lệ cá lia thia đực. ABSTRACT Lia thia fish commonly called the Siamese fighting fish (Betta splendens) is a specific freshwater aquarium fish, which raising as pet or for entertainment through fish fighting. This study aimed to find out the appropriate dosage of 17α - Methyltestosterone (17α - MT) hormone supplemented into feed to enhance masculinization rate of Siamese fighting fish. Frys after completing yolk digestion were fed with 17α - MT supplemented feed continuously for 21 days at dose of 0, 20, 40 and 60 mg 17α - MT per kg of feed, respectively treatment of NT1, NT2, NT3 and NT4. Fingerlings were kept being grown for up to 60 days of age to determine the growth, survival and transsexual rates on fish. The results showed that growth and survival rates of fish were not significantly different among treatments (p>0.05). Male rate and the fin lengths of fish in treatment of NT3 were statistically higher than those treatment of NT1 and NT2 (p<0.05); however, there were not significant difference compared to treatment of NT4 (p>0.05). Masculinization rate (93,8%) and masculinizing efficiency (84,6%) in treatment of NT3 were highest and there was statistically significant difference among the treatments (p<0.05). This research showed that supplement of 17α - MT into the feed at a dose of 40 mg 17α - MT per kg of feed increased the rate of male Siamese fighting fish.

Acute and Chronic Toxicity of Endocrine Disruptive Heavy Metals and Pesticides Exposed to Freshwater Fish P. reticulata and P. sphenops

Environmental monitoring is a recent world-wide approach to save the future in line. The present study focuses on toxicity of heavy metals and pesticides on the freshwater aquarium fish (Poecilia reticulata and Poecilia sphenops). The study intense on drawing the acute and chronic safe levels of metals and pesticide exposed to 96 h and 28 day respectively. On exposure, the fish were observed to be under stress and showed excitability. It was observed that both species were highly sensitive to arsenic and cypermethrin, meanwhile resistant to cadmium and chlorpyrifos. The acute safe levels for As irrespective of species was comparatively lesser than that of Cd exposed fish and the range of safe values for pesticides exposure were between 0.018 and 0.059 ppb. As the water quality is influencedby many environmental factors, the present study helps the aquarist in monitoring the safe level of toxicants in the medium. This in turn increases the economic growth of the aquarist.

Using Inter Simple Sequence Repeat Multi-Loci Markers for Studying Genetic Diversity in Guppy Fish

Aquarium fish industry has become a capacity for job creation and income generation. Aquarium fish uses for decoration and creating tranquility in the environment and beautification in public places. This study was conducted to investigate genetic variation between different populations of various varieties of guppy ornamental aquarium fish using inter simple sequence repeat (ISSR) markers in Iran for the first time. DNA was extracted from twelve strains. Polymerase chain reaction was performed using seven ISSR primers. GenAlex 6.501 and XLSTAT software was used to analyze data. Results of analysis of molecular variance showed that 54% of observed polymorphism belongs to variance among populations and 46% corresponds to diversity between populations. The highest and the lowest polymorphism percentage belonged to (GAG)5GC (90%) and (AG)8C (41%) markers, respectively. Percentage of polymorphic loci ranges from 32.31% to 86.15%. The results of phylogenetic tree showed that this tree was divided into 2 major clusters. Cluster I included only 2 populations and cluster II contained other 10 studied populations. It is suggested that this marker system was found to be efficient in discriminating each genotype at the molecular level and can be used for genetic diversity analysis for aquarium guppy fish because a greater understanding of the potential of the species is necessary for supporting long-term genetic improvement.

Effectiveness of Chironomid Larvae in Compare to Other Fish Foods on Growth Parameters and Body Protein of Two Economically Important Fishes

With the increasing human population, the demand for healthy, nutritious but cheap food also increasing day by day. The product of aquaculture mainly fish is more efficient to improve global food security. Along with the seafood, the effort is going on for more production of freshwater fish. For that reason, proper growth and sufficient proximate principles in fish are essential with a low-cost but healthy fish diet. Trichogaster fasciata and, Heteropneustes fossilis were fed with fourth instar larvae of Chironomus striatipennis (F1), dry Tubifex (F2), and granular floating type aquarium fish food (F3) respectively to observe the nutritional effect of different fish meal. Fish fed with F1 showed effective food conversion ratio and specific growth rate in comparison to fish fed on F2 and F3 respectively. The average daily gain was 214.3 % and 47.61% respectively in two fish when fed with F1. Percent gain weight increased from 1.12 (7th day) to 15.03 (28th day) in T. fasciata and 1.497 (7th day) to 8.21 (28th day) in H. fossilis when fed on F1. The result also showed that the protein level was increased steadily in both fishes when fed with F1 in comparison to other foods. It may be concluded that live larvae of Chironomus striatipennis were more effective fish food than dry Tubifex and aquarium fish food. It is a natural organic fish food with a negligible wastage used for fish and keeps the culture medium clean and debris-free with an ecofriendly environment.

Anaesthesia of laboratory, aquaculture and ornamental fish: Proceedings of the first LASA-FVS Symposium

Following on from the Annual Fish Veterinary Society Conference, this symposium was organised with the Laboratory Animal Science Association and brought together experts from ornamental (pond and aquarium) fish practice, aquaculture and aquatic-research facilities to discuss good practice of anaesthesia. This proceedings paper gives an overview of relevant experiences involving a range of immersion drugs including tricaine, benzocaine and isoeugenol, as well as a summary of the main topics of discussion. While fish anaesthesia is commonplace, administration methods, drugs and monitoring procedures may often be regarded as antiquated when compared with mammalian practice. These limitations notwithstanding, individual fish will benefit from good anaesthetic monitoring. Although the most common anaesthetic drugs may be perceived as equally efficacious and therefore interchangeable for different settings, challenges are different for the anaesthesia of grouped fish, when determining species-dependent anaesthetic dosing in a multi-species tank, or adapting to farming requirements, nationally licensed products, costs and withdrawal periods. The fish anaesthetic arsenal fails to address premedication, analgesia and issues of averseness. The two latter factors should be part of the evaluation of anaesthetic protocols; therefore, instructions for the analgesic provision of lidocaine to fin clipped zebrafish are proposed. Euthanasia practices could sometimes be refined too. Alternative physical methods such as electrical stunning are options to be considered.

The reproduction viability of Indonesian endemic fish Oryzias marmoratus (Aurich, 1935) fed by Spirulina

Oryzias marmoratus is one of the ornamental aquarium fish species that live endemic to Towuti Lake, South of Sulawesi, Indonesia. However, the fish has been categorized as near threatened by IUCN. A current report showed the fish could be cultivated. This research aims to improve the reproduction quality in cultivation by using artificial feed containing Spirulina (A=0, B=3, and C=6) % dry weight. The study was conducted with two replications using an aquarium (80 x 40 x 40 cm) for 40 days (October-December 2020) at Research Center for Limnology-LIPI. Each aquarium contains 21 broodstock (female: male = 2:1). Observation parameters are the total number of spawning/ToS (time), ovulated eggs number/OEN, fertilization ability/FA (%), hatching ability/HA (%), number of larvae/NoL, the egg of incubation time/EIT (day), survival of larvae seven days old after hatching/SR7 (%). Based on descriptive analysis, the use of feed C (containing 6% Spirulina) produced the highest values of ToS, OEN, %HA, NoL, and SR7 (%) were ten times; 89 eggs; 89 larvae, 100%; and 98.89±3.51% respectively. Spirulina could increase the reproduction viability and is presumed to enhance feed efficiency of Oryzias marmoratus, but the optimum levels have not been obtained.