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Salt is a common and relatively inexpensive treatment for fish. The use of non-iodized table salt or rock salt (suitable for consumption by humans or livestock) is acceptable for treatment. For ease of application, many pond owners use 50 lb salt brine blocks. "Brine" blocks are salt blocks. Granular salt can also be purchased in bags or bulk.
Seawater contains 3% (30,000 ppm) salt concentration. Two hundred ppm (200 ppm) to 500 ppm can be used as an indefinite treatment in ponds to relieve stress. Ten thousand ppm (10,000 ppm) to 30,000 ppm can be used as a prolonged treatment in tanks for 30 minutes or until fish show signs of stress. Thirty thousand ppm (30,000 ppm) can also be used as a quick dip (60 seconds) in treatment tanks. To achieve 30,000 ppm in a tank, you add 2 1/2 lbs of salt for every 10 gallons of water. For ponds, 1 ppm is equal to 2.7 lbs/acre-ft of water. You need to know how many acre-feet of water you have in your pond (surface acres x average depth) to determine the treatment rate.
Two aquaculture tours to showcase aquaculture production and fee fishing will be offered on December 3 and December 7. On December 3, a tour of Grandfather Trout Farm, Banner Elk, and Hump Mountain Trout Farm, Elk Park, will take place. Grandfather Trout Farm is a fee fishing operation located in near Boone. Hump Mountain Trout Farm is a fingerling and food fish producer located in Elk Park. Both of these facilities have been in operation for years.
On December 7, a tour of Creekside Carp & Catifish Lakes and Whitmar Lakes will take place. These facilities also have been operating for years. If you ever considered aquaculture as a business venture this is your chance to see some fish farms first hand. this is your chance to talk with the business owners. A van will be available for transportation and will leave Mario
n at 9:30am on both days. Return time scheduled for 4:00pm on December 3 and 3:30pm on December 7. You are welcome to drive to the facilities as well. Registration is required by December 1 and cost is $5.00. Make checks payable to McDowell County Center. Space is limited, call early. Call Cheryl Mitchell or Molly Sandfoss at 828-652-7874.
Skip Thompson wrote about Bacterial Coldwater Disease in his last version of Trout Aquaculture Newsletter volume 19 number 1. Here is what he has to say about it...
Bacterial Coldwater Disease (BCWD) is usually seen when water temperature is between 60-70 oF. One sign of the disease is the erosion of the tail (caudal) fin. Another sign is a discolored area above and slightly in front of the anal fin that becomes an ulcerated lesion that looks like a 'scooped-out' area.
BCWD usually affects trout less than 6" in size but chronic mortality can be seen in fish larger than 6". As the disease progresses, trout can be seen with the entire caudal fin missing with erosion of the peduncle or fleshy part just in front of the fin. Another name for the disease is peduncle disease.
Prevention & Control
BCWD can apparently enter trout eggs and is not sensitive to a standard treatment of 100 ppm iodophor (Wescodyne, Argentyne, etc). Instead eggs should be disinfected with Hydrogen Peroxide at 100 ppm (4.1 mL/gal of water at 35% active ingredient) (28.7 mL/gal of water at 5% active ingredient).
Routine flow-through treatments at 1.0-1.5 ppm Hyamine® or other quaternary ammonium compounds reportedly are effective in prevention and in the early stages of infection. However, this approach is not effective once the disease has progressed to erosion of the peduncle and caudal fin.
Stress associated with rearing density contributes to higher level of mortality. In fact, the level of mortality usually will decrease if the trout are simply split into two or more raceways, lowering the density. Mortalities and trout showing the symptoms should be removed quickly since dead trout shed almost 70 times more bacterial than live trout.
If you choose to use an antibiotic, Terramycin® (oxytetracycline) is not effective when used at the approved rate of 2.5-3.75 g/100 lbs of fish for 10 days. However, Terramycin® is reportedly effective when used at 16.5 g/100 lbs of trout for 10 days.
Aquaflor® was approved for use in March 2007 against BCWD at 0.454 g/ 100 lbs of trout for 10 days, and the withdraw period is 15 days. It is worked well in North Carolina. In most instances with BCWD, it is best to first reduce the fish density and then use the antibiotic.
