| There is also a rapid growth of "environmental" bacterial populations in water after standard hatchery treatments like Ultraviolet sterilization and Ozonisation. Although both UV and ozone are very effective in the sterilization of water, any bacteria that enters the water after this process could flourish without competition. These can be wind-borne or even from a finger tip or a single hair. No commercial hatchery can completely exclude bacteria from their larval rearing systems. The principle behind probiotic application is to recognise this fact and introduce an ecosystem of benign and beneficial bacteria to the culture system. These non-pathogenic bacteria will occupy the various ecological niches and so out compete potential pathogens. Some, like the nitrifying bacteria provide additional benefits through improving water quality by reducing ammonia and nitrite levels. |
| Over the years, I have tested a few probiotics, but there are far too many on the market for me to test all. I had a problem similar to zoea syndrome, but that could develop in any stage. The protozoea, mysis or PL's would get a pink appearance, stop eating, get pale and die. A few dead larvae apparent in a sample of water is an indication of a high mortality rate. Often, at postlarval harvest, many pink dead postlarvae would be found on the floor of the larval rearing tank. Treatment with antibiotics had little effect. Once this problem became established in a system, it was difficult to get rid of. Hence, many experienced hatchery managers running large hatcheries follow a policy of complete shutdown and system dryout when persistent bacterial problems develop. A complete shutdown will usually follow the failure of antibiotics to control the bacterial outbreak, even though a supporting microbiology department is testing various antibiotics to see which is the most effective treatment for the problem encountered. Complete shutdowns and hatchery dryouts are expensive solutions affecting stocking plans that may be critical. Another strategy employed is to spawn and fill the hatchery as quickly as possible - as little as three days - and then try and complete the larval cycle before the pathogens appear. This remedy will put unreasonable demands on broodstock sources and maturation facilities. |
| I now have a probiotic that handles this problem in a different way. I have success with a combination of Alken Clear-Flo 1006 http://www.alken-murray.com/1006pib.htm and Alken Clear-Flo 1100-50x http://www.alken-murray.com/1100-50xpib.htm. I also use EDTA at 10 ppm in the larval rearing. I use the two probiotics as specified for smaller tanks. In a 10T LRT, I will inoculate with small amounts to start, sometimes in nauplius stage and sometimes in zoea 1 or 2 stage, depending on the overall hatchery condition. Initially I also spread this probiotic widely - into my maturation tanks, water storage tanks, spawning tanks, artemia tanks, splash down floors and drains etc. In this way, the probiotic is allowed to occupy the whole area. It will take about 2 weeks for a very evident change to take place. |
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E-mail Alken-Murray Corp: aqua@alken-murray.com E-mail author, Laurence Evans: web@ecotao.com | ||||||