Brachionusrotundiformis - Live Feed - Lab Report Example

Live Feed Live Feed Rotifers In the current trend of aquaculture, two types of rotifers are being used. They include the Brachionusrotundiformis that was formerly known as S or SS-type and the (Brachionusplicatilis, commonly referred to as L-type. Rotifers have proven to be very fast as far as reproduction is concerned. In this case, 1,000 rotifers can become 1,000,000 in 5 to 7 days. In addition, these organisms are quite small; their length lies between 60 and 350 um. However, this range differs depending on species. Rotifers swim very slowly in water. As such, it is easier for fish to capture them for food. They are highly nutritious though they can still be enriched to be even more nutritious. Lastly, rotifers have a short lifespan of between 3.4 days to 4.4 days at 25c. However, there population is greatly affected by stress. Water Quality: They survive well at a narrow range of temperature between 20and 30c. The optimum oxygen concentration in water should be kept well above the saturation level. The pH range should be between 6.6 and 7.5. Below this rotifers will die in large numbers. Other favorable conditions for optimum for their normal growth are salinity of 5 – 35 g/L and low level of toxicity in water. Culture Set Up: This involves setting up favorable conditions that will allow maximum production of rotifers. Most importantly, the tank should be disinfected and rinsed properly before making the setup. Then, the tank is filled with filtered saltwater and freshwater together with oxygen stones and standpipe. The content of the tank is then neutralized using 5g of sodium thiosulfate for every 100L of fresh water. Rotifers are then added together with initiated pulse feed by the use of peristaltic pumps of batch diet. To know whether the Rotifers cultures are fit rotifers will be swimming rapidly with the female laying eggs. In addition, bacteria and ciliates will be present. A poor culture will be characterized with cloudy water and bad odor. Culture Maintenance For maximum output, there are some minimum maintenance practices that should be ensured. They include daily feeding, siphoning out of old water and replacing it with fresh one, removing solid particles suspended on water, full harvesting after every 4 to 5 days and maintaining a back up culture in case of an emergency evacuation. Feeding Rotifers There are two levels of feeding: maintenance diet and enrichment diet. Maintenance diet involves live microalgae, commercial food, frozen microalgae (RotiGroNanno) and a mixture of algmac and yeast. Enrichment diet comprises probiotic, algae paste, live microalgae and algamac products (commercial products) Rotifers Harvesting Methods the harvesting exercise starts when rotifers are siphoned and placed in a mesh harvester. In this case, they are them rinsed using clean salty water until the water is clear of particles and other wastes. After they are cleaned, the culture tanks are the cleaned in readiness for another generation of rotifers. To prevent the rotifers from bunching, a siphon hose should be used to drain them. in addition, a slow stream of water should be used to wash them. it is important to note that turbulent water will wash most of them away. Feeding Rotifers to Larvae Before feeding the larvae with rotifers, they should be enriched 3-24 hours prior using various enrichment products as it has been stated above. In addition, rotifers should be maintained in tanks with high densities prior to feeding. After that, rotifers are ready to be fed to larvae. They can be fed 3-5 times a day. Further, live algae of algae paste can be used in the green water technique. After feeding the larval, the remaining rotifers should be counted before more are added. Artemia Artemia is mostly used by farmers who seek to reduce the cost of labour. This is because rearing them is requires the low labor intensive. Artemia start weaning after 7 to 10 days. In this case, they start out in the form of cyst and hence they require to be hydrated. Artemia goes through two stages; first larval stage (Instar I) that exclusively feeds on yolk sack and the Second Larval stage(Instar II) that that feeds on small particles. Artemia Harvest Procedure When harvesting artemia, a hydration cone is used. In this case, it is filled with water the water is chlorinated with 75ml of chlorine and aerated then cyst is added before emptying into Atemia-designated bucket. A hatch cone is then prepared by filling it with UV filtered seawater and allowed to sit for minimum 6hrs. Then, the hatch cone is neutralized with sodium thiosulfate and 1g/2L of baking soda while adding light oxygen via stone. After the content has been prepared, Artemia cysts are added and the system allowed standing for 24hours. After 24 hours, the newly hatched artemia are placed in harvesters where they are rinsed with UV filtered water. To filter the artemia, they are passed though a double 150um meshed filter. Then, the harvester adds harvester bin into an enrichment cone that is highly aerated with heavy oxygen, enrichment (85%-3050, 10%ARA and 5%-Astaxathin) and proboatics (probiotics (50 mL=1mL probiotic/L of seawater in cone)). 12 hours later, the artemia are siphoned from the harvester bin and then they are counted under the microscope. Water Quality for rearing artemia Just like rotifers, artemia culturing requires high concentration of oxygen in the water. Optimally, 5mg of oxygen per liter of water is ideal. The temperature should be maintained well above 25c. However, temperature above 28c is not good. The pH should be maintained at 8 while the salinity should be 5 to 35g/L. the cyst density should be between 5g/L and 2 g/L for large volume. Lastly, conical tanks that are illuminated with 2000 lux of light are optimum. In summary: The rotifers should be fed with 2 or 3 per ml of their food in the third day. This depends on the size of the larval mouth. Between 3 and 7 days, they should be fed at percentage of 100% to 300%. This should continue until they are 12 days old. In the 8th day, 0.05 to 2art/ml of artemia is introduced. In this case, both artemia and rotifer are alternated after every 30 minutes. In the 12th day, the tanks should be cleaned by removing any remains of uneaten foods. In this case, 1000um mesh wire is used. Lastly, dry feed is introduced in the 15th day. This continues days 25 to 28 Read More