Aquaculture Submissions

Aquaculture Submissions to ADDL - Purdue University

 Aquaculture case submissions range from one fish submitted by a fish hobbyist to numerous fish from large private or zoological collections, food-fish producers, or pet-fish suppliers. With the increasing number of hobbyists as well as the emerging aquaculture industry in Indiana, the number of aquaculture case submissions is rapidly increasing.

 It is imperative to note that the condition of the fish sample submitted dictates the outcome of our diagnostic investigation in many instances. Care must be taken in collecting an adequate sample and transporting this sample to our lab.

 The best sample for submission is an acutely affected, live fish exhibiting clinical signs or having gross lesions of disease. Clinical signs of disease are usually limited to anorexia, lethargy, abnormal swimming or position in the water column, "flashing" (rubbing of the body against a substrate in the aquatic environment), and the loss of fright response. Gross lesions include exophthalmia (unilateral or bilateral), ascites, skin erosions or ulcers, missing scales, frayed fins, or hemorrhage of the skin, eyes or fins. If small fish (less than 4 inches, head to tail length) are involved in the outbreak, 6-8 fish should be submitted. If these fish represent a single disease process, as determined by the pathologist, then tissues are commonly pooled, and a single case accession fee is assessed.

 The best and most assured method for transporting fish to the lab is hand delivery with the fish in a clean bucket, plastic or styrofoam cooler with water from the environment from which the fish originated. If transportation time is greater than 1-2 hours, it is recommended that a small battery operated aerator be used for supplemental oxygen. For shipment of fish, place fish in a large thick transparent plastic bag filled approximately 1/3 full with water. An "air cap" or oxygen should be present immediately above the water surface, occupying at least 1/3 to 1/2 of the plastic bag. The bag should be sufficiently tied and placed inside another bag to prevent leakage. This bag should be placed within a thick, wax-coated cardboard box for shipping. This box, along with the submission form, can be shipped via UPS or another appropriate overnight carrier company.

 Since many aquaculture cases are associated with water quality problems, it is a good practice to submit a water sample with the fish submission. We are able to perform all of the standard water quality tests on water samples except for the dissolved oxygen (DO) concentration. This water quality parameter is best evaluated "on site" since it changes rapidly in a sample container. THIS WATER SAMPLE MUST BE SUBMITTED SEPARATELY, i.e., without fish. This water sample should be submitted in a clean one quart jar with a screw top lid (i.e. canning jar) with a layer of aluminum foil placed between the water sample and the lid. Water samples shipped in this manner are also satisfactory for pesticide or herbicide analysis as well as testing water quality parameters.

 If recently deceased fish are the only sample available to the veterinarian for diagnostic evaluation, the best results are obtained by having the veterinarian take tissue samples for submission. Culturette swabs, with transport media, of the liver and spleen are the best bacteriologic samples for submission. The internal organs including gills, liver, spleen, gastrointestinal tract, integument, skeletal muscle, etc. can be submitted for histopathology in 10% formalin solution. Alternatively, if the fish is less than 3 inches in length, it may be submitted "whole" in formalin after opening the abdominal cavity to expose the internal organs to fixative.

 If herbicides or pesticides are suspected, it is imperative to take a water sample from the pond or lake IMMEDIATELY. Detection of certain herbicides and pesticides can be made from frozen fish fillets, so filleting of the fish and freezing before shipment is the best way to prepare samples for shipment. The following table emphasizes the important points of this article.

 A short history should be included with each submission. Husbandry, water quality problems, stocking densities, size of the tank/pond/lake, approximate mortality and morbidity, algal bloom history, origin of the fish, date and time of onset of current problem are all very pertinent issues to remember when completing the history portion of the submission form. Please feel free to contact us if you have questions regarding aquaculture submissions.

 - by Tim Muench, DVM, MS

- edited by M. Randy White, DVM, PhD