Open Access Original Research Article

The Effect of Potassium Diformate Addition to Feed on Growth and Survival Rates of Common Carp (Cyprinus carpio L.)

Ayi Yustiati, Mahmud Sa’id, . Junianto, Ibnu Bangkit Bioshina Suryadi

Asian Journal of Fisheries and Aquatic Research, Page 1-8
DOI: 10.9734/ajfar/2020/v10i430186

This research aimed to determine the optimal dosage of potassium diformate addition to commercial feed in order to increase the growth and survival rate of common carp seeds. The method used in this research was experimental in a completely randomized design (CRD) consisting of five treatments and four replications. The treatments used were A (control), B with addition of potassium diformate (0.2%), C (0.3%), D (0.4%), and E (0.5%). For test fish, there were 200 of Common carp seeds with a size of 2-3 cm. The media used was 20 aquariums with a size of 40x30x40 cm3 and a stocking density of 10 individuals/aquarium. The rearing period was 35 days and the amount of feed given was 3% of the fish body weight. The parameters observed included water quality (temperature, pH, and dissolved oxygen) which were observed every 7 days for 35 days. Other parameters  monitored were daily growth rate, survival rate, feed efficiency, and the acidity level of the intestine. The results showed that 0.3% addition of potassium diformate gave the best results with a daily growth rate value of 3.21%, highest survival of 98%, efficiency of feed utilization of 64.83%, and a decrease in intestinal pH which helped the process of protein absorption in the fish body. In conclution, the addition of potassium diformate has good effect on growth and survival rates of common carp.

Open Access Original Research Article

Ethnoichthyological Study of Biological Characteristics and Ecology (Salminus brasiliensis: Teleostei/Characiform): Importance, Status and Conservation Challenges in the Region of Mato Grosso, Brazil

Elisangela Santana de Oliveira Dantas, Diniz Pereira Leite Júnior

Asian Journal of Fisheries and Aquatic Research, Page 9-34
DOI: 10.9734/ajfar/2020/v10i430187

Introduction: Salminus is a genus of ichthyofauna currently constituted by five species of migratory neotropical fish, predators, which are important in commercial, ecological and sport fishing.

Aims: The article reflects the conception of fishermen about the ecological interrelationships of ichthyofauna, the relationship with sport fishing, aspects of trophic interactions among fish, the use of habitats aimed at feeding or reproduction and relations with fishing activity.

Methodology: Study carried out in the state of Mato Grosso, central region of Brazil. 122 fishing professionals and artisanal fishermen were interviewed. The testimonies were obtained through phonographic interviews, carried out during visits in temperate sport fishing from 2018 to 2020, verifying questions related to fishing and the study specimen S. brasiliensis.

Results: Among the interviewees, 37 were sport fishermen (30.3%), 22 artisanal fishermen (18.1%) and 63 guide fishermen (51.6%). The interviewees reported several situations and approaches on the problems generated by sport fishing in the State. The results were consistent with the scientific literature and revealed detailed knowledge about the survival strategies of S. brasiliensis. The answers revealed the fishermen's observations on the decrease in fishing resources, the scarcity of species and the conflicts related to sport fishing, making it necessary to look for the best ways of recovering and conserving native species and monitoring in the surveyed places.

Conclusion: S. brasiliensis is an example of the ichthyofauna that is much sought after by sport fishing. The interviewees demonstrated important perceptions of the changes that are occurring in the rivers of Mato Grosso and it was found that it is necessary to intensify studies looking for ways to recover and conserve the native ichthyofauna in the region. The results obtained aim to promote social contributions and partnerships with professional and artisanal fishermen, encouraged to achieve a better harmony between fishing and nature, creating actions that can be extended to indigenous, quilombola and riverside peoples.

Open Access Original Research Article

Causation of Saddleback Deformities in The Yellowfin Bream Acanthopagrus australis Fishery: Evidence of Physical Injury

Barry Pollock

Asian Journal of Fisheries and Aquatic Research, Page 35-48
DOI: 10.9734/ajfar/2020/v10i430188

The yellowfin bream A. australis supports an important commercial net and angling fishery on the east coast of Australia. Saddleback, a deformity of the dorsal fin and profile, occurs in this species, with the occurrence of fish with saddleback being as high as 10% in some areas. The present study provides new information and analysis of causation of the saddleback deformity in the yellowfin bream fishery. Lateral line scale regeneration due to injury, and soft tissue abnormalities indicative of deep wounding are present in yellowfin bream with saddleback. X-ray images of the entire skeleton of specimens with saddleback were also examined. An unpublished government report on chemical residues in saddleback and normal yellowfin bream is appended and discussed. The absence of both chemical residues, and lack of other skeletal deformities in yellowfin bream with saddleback provide indirect evidence of physical injury as the cause of saddleback in this case. The role of discarding of meshed yellowfin bream, which are smaller than the legal minimum size, as causation of the saddleback deformity is evaluated.

Open Access Original Research Article

KHV Detection Based on Thermal Lysis - Nested PCR (Polymerase Chain Reaction)

Ibnu Dwi Buwono

Asian Journal of Fisheries and Aquatic Research, Page 49-57
DOI: 10.9734/ajfar/2020/v10i430189

In the case of common carp (Cyprinus carpio) and goldfish (Carrasius auratus) that were lightly infected with Koi Herpes Virus (KHV), the use of the one-step PCR method was insensitive to detect the presence of KHV DNA. The nested PCR method has been developed for a more sensitive detection system for KHV infection. This study aims to test the sensitivity of one-step and nested PCR methods in detecting the KHV virus in lightly infected common carp to prevent early disease attacks. DNA extraction of the test samples used thermal lysis and PBS (Phosphate Buffered Saline). DNA isolate as a KHV template was used to amplify KHV sequences using KHV-TKf: 5'-GGGTTACCTGTACGAG-3 'and KHV-TKr: 5'-CACCCAGTAGATTATGC-3' primers in the one-step PCR method. The nested PCR method uses two pairs of primers, namely the KHV-TKf: 5'-GACACCACATCTGCAAGGAG-3' and KHV-TKr: 5'-GACACATGTTACAATGGTGGC-3') and the CEFAS primer pair (5'-CGTCGTGAGGAATACGACG-3' and 5'- ACCGTACAGCTCGTACTGG-3') for amplification of KHV sequences. The one-step PCR method was insensitive for detection of KHV in common carp and goldfish infected with viruses without clinical symptoms, and was sensitive enough to detect viruses with mild symptoms with a DNA fragment size of 409 bp using TK primers. The nested PCR method was more sensitive in detecting KHV DNA in fish without clinical symptoms with a DNA fragment size of 348 bp using CEFAS primers.

Open Access Original Research Article

The Effect of Sudden Rise in Salinity on Survival Rates and Salinity Tolerance Ability of Ctenopharyngodon idella

Mohammed Shaker Alkhshali, Hasan Ali Alhilali

Asian Journal of Fisheries and Aquatic Research, Page 58-63
DOI: 10.9734/ajfar/2020/v10i430190

This study aimed to identify the extent of the effect of sudden rise in salinity on survival rates of Ctenopharyngodon idella and determine the lethal concentration (LC50) that kills half of the number of fish. The fish were suddenly exposed to lethal concentrations (LC50 values) of: 4, 8, 12, and 16 g / l at a weight of 31.4 ± 2.2 g, as well as hypertonic water at the rate of (0.1 g of LC50), which was considered as a controlling sample. The (LC50) were prepared by adding a known weight of dried sea salt in a liter of chlorine-free hypertonic water until the required lethal concentrations (LC50) were reached. The results of the survival rates experiment showed that the survival rate of Ctenopharyngodon idella reached 90%, 20% and 0% at the lethal concentration (LC50) of 8, 12 and 16 g /I respectively, while the survival rate was 100% in both hypertonic water and the lethal concentration (LC50) of 4 g / l.

The results of the experiment to determine the lethal concentration (LC50) that kills half of the number of fish also showed that the LC50 in Ctenopharyngodon idella reached 9.68 g / l during 96 hours of sudden exposure to LC50 at the rate of 0.1, 4, 8, 12 and 16 g / l. During the experiment, the fish were fed on food ration containing 32% protein, at the rafe of 3% of the weight of fishs' body.