Determination of Some Heavy Metals in Cultured Nile Tilapia (Oreochromis niloticus) in Western Kordofan State, Sudan

The current study was conducted in two different localities have been selected in Western Kordofan State (Elsonout and Abu-zabad Localities) to evaluate some heavy metals concentrations (Copper, Cadmium, Zinc, and Lead) in three parts (liver, gills and muscles) of Nile Tilapia (Oreochromis niloticus) cultured in Dams, also to evaluate the same heavy metals concentrations in Dams water where Nile Tilapia is cultured. The evaluation was included the correlation of heavy metals accumulation between fish organs and water samples were compared. Finally, the results were compared with recommended levels by FAO, WHO and other international organizations. A total of 54 samples has been taken from marketable size Nile Tilapia parts (gills; livers and muscles) and subjected to analysis of heavy metals accumulations. Also, a total of 18 water samples were taken from Dams (shallow, middle and deep water). The data was subjected to SPSS using ANOVA. The findings of this work were revealed that, there were a highly significant differences (P≤0.01) in all heavy metals among gills, liver and muscles of Nile Tilapia cultured in Dams. And there was a highly significant difference (P≤0.01) in all heavy metals among gills, liver and muscles of Nile Tilapia according to localities. Anyway, when compared fish organs; we found that, gills were recorded the maximum figures in all heavy metals followed by livers and the minimum figures were recorded by muscles. The results of this study were in the permissible levels recommended by international organizations.

Short term culture of wild caught juvenile rabbit fishes (Siganus javus) in open sea cages at Palk Bay

Objectives: The main objective of the study was to collect and rear the unmarketable, small sized S.javus which is mostly rejected by the traditional fisherman. During fishing activities, under sized S.javus ranging in sizes from 25 to 40 kg (< 30-40 % of total catch/day) is being captured. Due to very low marketable value these small fishes (<250 g) get rejected. Therefore, we utilized this as an economically viable option for utilization as seeds for rearing until they reach the necessary marketable size. Methods: Undersized juveniles (12-16 cm, 40 -55 g) were collected from nearby Olaikuda village,Rameshwaram using traditional traps made using bamboo and odai tree bark (Acacia planifrons). The collected juveniles were stocked in sea cages and fed with locally formulated plant based feed containing 28-32 % crude protein. Findings: Harvesting was successfully done after 140 days with 90 % survival. The average growth rate achieved was 2.5 g /day with FCR of 2.01. This resulted in an average harvest size of 400 g/fish from its initial stoking size of 50 g with an attracted market value of Rs. 150/kg. Novelty: Till date, no attempts were made to commercialize such harvesting techniques for the species Siganus javus in pilot scale in India (Except James, 1984). Keywords: Rabbit fish; Siganus javus; sea cage culture; rabbit fish culture; Siganidae

Testing a Model of Pacific Oysters’ (Crassostrea gigas) Growth in the Adriatic Sea: Implications for Aquaculture Spatial Planning

Assessing the potential biomass yield is a key step in aquaculture site selection. This is challenging, especially for shellfish, as the growth rate depends on both trophic status and water temperature. Individual ecophysiological models can be used for mapping potential shellfish growth in coastal areas, using as input spatial time series of remotely sensed SST and chlorophyll-a. This approach was taken here to estimate the potential for developing oyster (Crassostrea gigas) farming in the western Adriatic Sea. Industry relevant indicators (i.e., shell length, total individual weight) and days required to reach marketable size were mapped using a dynamic energy budget model, finetuned on the basis of site-specific morphometric data collected monthly for a year. Spatially scaled-up results showed that the faster and more uniform growth in the northern Adriatic coastal area, compared with the southern one, where chlorophyll-a levels are lower and summer temperatures exceed the critical temperature limit for longer periods. These results could be used in planning the identification of allocated zones for aquaculture, (AZA), taking into account also the potential for farming or co-farming C. gigas. In perspective, the methodology could be used for getting insights on changes to the potential productivity indicators due to climatic changes.

Seed production and grow-out of walking catfish (Clarias macrocephalus).

Ponds for catfish broodstock range in size from 500 to 1,000 m2, with a depth of 1-1.2 m. The stocking density of broodstock ranges from 0.2 to 0.3 kg m-2. The catfish are fed with fresh feeds such as snails, small prawns and trash fish. Farm-made feeds are also used for feeding. In the artificial spawning process, the ripe eggs are obtained by gently pressing the abdomen of the gravid females. The testis from the male has to be taken out from the fish to fertilize the eggs. The fertilized eggs are spread on the surface of a net in running water for incubation and hatching will occur in 22-24 hours. Nursing from fry to fingerlings is carried out in earthen ponds, which range in size from 500 to 1,000 m2 at a density of 200-500 fish m-2. Natural feed is cultured in the pond before stocking the fry for nursing. Supplementary feed, which is homemade, is also given during the nursing period. The fish reach 3.5-5.0 cm after 25-30 days of nursing. For grow-out ponds that range in size from 500 to 1,000 m2, stocking density is from 25 to 30 fish m-2. The fish are fed with trash fish, small prawns, snails, slaughterhouse by-products and commercial feed pellets. Fish reach marketable size of 350-400 g, or above, after 7-8 months of culture.

Seed production and grow-out of sand goby (Oxyeleotris marmoratus) in Vietnam.

Pond area for broodfish ranges from 500 to 1,000 m2 with a depth of 1-1.2 m. Broodfish density ranges from 0.2 to 0.3 kg m-2. Fresh food such as snails, small prawns and fish are used to feed broodfish at a feeding rate of 3.5% of total body weight per day. Water exchange is done periodically at 20-30% of total volume per time. Sticky eggs of sand goby adhere to substrates. Hatching takes place 22-48 hours after fertilization. A suitable temperature is 28-29°C and pH at 6.5-7.5. Nursing fry to fingerlings is carried out in ponds at a stocking density of 300-500 fish m-2. After nursing for 50-60 days, they can reach the size of 3 cm. Large fingerlings of 15-30 g are obtained after at least 3 months of nursing. Continuing nursing up to 5-6 months gives larger fingerlings (60-80 g) for grow-out. Stocking density is 5-10 fish m-2 in grow-out ponds and 30-40 fish m-2 in cages. Fish, small prawns, snails and by-products from slaughterhouses are used to feed the fish. They can reach a marketable size of 500 g or more after 6-7 months of culture.

REARING TRIAL ON BOTIA (Chromobotia macracanthus Bleeker 1852) BROODSTOCK POTENTIAL ORNAMENTAL FISH WITH AND WITHOUT SHELTER

Botia fish (clown loach) growth is relatively slow, taking 4-5 months to reach marketable size (2 inch) and 3 years to achieve initial gonad maturation in female and 1 year in male fish. Environmental degradation and overfishing are factors triggering the production of newly potential broodstock. This study aimed to observe the growth response of potential broodstock through rearing technique with and without shelter. Fish were kept inside the aquaria sized 80x40x30 cm with 20 cm water height on the recirculation system. Fish used for shelter treatment were: Total length ± 7.7 cm, height ± 2.09 cm, and weight ± 7.33 g; for no shelter treatment were: Total length ± 6.7 cm, height ± 1.88 cm, and weight ± 4.59 g. Fish were stocked 10 fish / aquarium and fed 3 times / day by at satiation method. Parameters observed were total length, height and weight improvement also water quality. The results showed that growth and feed efficiency had better value when reared with shelter than without shelter.

Population density, multiple harvesting, and ability of Ipomoea reptans to compete with native weeds at tropical wetlands

Lakitan B, Kartika K. 2020. Population density, multiple harvesting, and ability of Ipomoea reptans to compete with native weeds at tropical wetlands. Biodiversitas 21: 4376-4383. Despite as a nutritious, fast-growing, and well-adapted leafy vegetable at tropical wetlands; Ipomoea reptans has not been intensively cultivated yet. This study was designed for increasing productivity of this vegetable by optimizing population density, extending harvesting period, and its ability to compete with native weeds at tropical wetlands. Bottom wet culture system (BWCS) was implemented by placing all pots within 2 m x 4 m experimental pool filled with water to 2-cm depth to make sure bottom part of the substrate within each pot was continuously water-saturated. Results of this study indicated that despite fluctuated yield at each harvest, accumulative yields after five consecutive harvests were not significantly different among population densities from 14 to 71 plants per m2. Yet, quality of yield in most cases was better in lower population density treatment (14 plants per m2), as indicated by SPAD value and marketable size of individual plants. Frequent NPK fertilizer application was effective for increasing yield. The first harvest was done at 4 weeks after seed sowing; thereafter, the plants were routinely re-harvested at about every week. This fast-growing vegetable also exhibited ability to compete with native weeds commonly found at tropical wetlands at density up to 11.3 mg cm-2.

Assessment of Hydraulic Conductivity of Some Nigerian Hardwood Timbers to Four Timber Treatment Chemicals through Quantitative Anatomical Studies

Aim: Hydraulic conductivity following the Hagen-Poiseuille Law is a quantitative approach to determine the treatability of wood by chemicals. The hydraulic conductivities of the ten selected Nigerian hardwood timber species to four wood treatment chemicals were estimated, using Hagen-Peiseuille equation. Materials and Methods: Ten timber species of marketable size and age were sourced from the forestry Departments of Enugu, Anambra and Abia States of Nigeria. Maceration were carried out following standard procedures. The viscosities in centipoises (cp) of the four wood treatment chemicals were measured in a viscometer test, while the hydraulic conductivities were calculated using the Hagen-Peiseuille equation. Results: The results obtained show that the different woods responded differently to the chemicals. Treatment with Folithion 200 showed higher conductivity in Triplochiton scleroxylon (9.01 mm-3S-1× 10-5), followed by Mansonia altissima, Milicia excelsa and Terminalia superb. The order of conductivity to treatment with Actellic 25EO was Terminalia superba > Mansonia altissima > Gmelina arborea, > Khaya ivorensis. Ceiba pentandra gave the highest conductivity of 8.58 mm-3S-1× 10-5, followed by Afzelia africana and Canarium schwenfurthii to the chemical Termitox. While Triplochiton scleroxylon gave the highest conductivity of 6.52 mm-3S-1×10-5, followed by Milicia excels and Terminalia superba to the chemical Solignum. Conclusion: Folithion 200 would be effective on Milicia excels, Mansonia altissima and Gmelina arborea, Actellic 25 EO would be effective on Khaya ivorensis, Terminalia superb and Antiaris toxicaria while Termitox would be effective on Ceiba pentandra, Afzelia Africana and Canarium schweinfurthii.

A review of juvenile redclaw crayfish Cherax quadricarinatus (von Martens, 1898) aquaculture: global production practices and innovation

The Australian Redclaw crayfish, Cherax quadricarinatus, has been the subject of aquaculture development for more than 3 decades. Farm production from Australia and from around the world for this species has been relatively low, as suitable production technology continues to develop. The production of redclaw juveniles for the purpose of stocking to ponds for on-growing to marketable size, has been a particular constraint and new approaches to breeding and mass production of craylings have provided renewed impetus to industry expansion. This paper reviews the literature concerning redclaw juvenile production and provides a status report of current practices and innovations that may support further expansion of redclaw aquaculture.