Hypothesis of Head and Lateral Line Erosion in Fish

Part - 3

Enhancing Immune Function with Nutrition

By: Terry D. Bartelme

Suppressed Immune Function and Nutrition

The immune system is debilitated by poor nutrition and cannot function to its full capacity without the proper nutrients. For this reason, fish with Head and Lateral Line Erosion will often respond positively to improvements in their diet.

Nutrition

Vitamins and highly unsaturated fatty acids (HUFA) are essential in the treatment of HLLE. Vitamin A, in particular, has been linked with HLLE as beneficial to healing. An important function of vitamin A is to maintain the integrity of the epithelial cells. Frozen broccoli and shredded carrots are a good source of vitamin A. B complex vitamins are helpful for treating stress in humans, but nothing conclusive has been reported relating to feeding fish vitamin B. Vitamin C has shown to increase resistance to bacterial infection and it is also important to tissue repair. Vitamin C is believed to help alleviate the effects of stress in fish. Vitamin E can increase the production of antibodies by the immune system. Vitamins C, A and E are known to enhance immune response in fish. Trace metals, in particular selenium, have proven to help with phagocytosis (the process by which white blood cells consume invaders). The same is true of vitamin E. Fatty acids increase the bactericidal activity produced by macrophages that fight infection (Blazer, 1991). Fatty acid enrichment is also helpful for enhancing stress resistance (Kraul et al., 1993: Ako et al., 1994).

In a study of salmonids in 1994 Waagbo concluded that vitamin E deficiency resulted in immunological malfunction and reduced disease resistance. There has been at least one study indicating that vitamin E reduces stress in mammals (Tengerdy, 1989). Fish fed animal protein appear to have better survivability than those fed vegetable protein (Neji et al., 1993). Spirulina and Euphausia Pacifica krill (plankton) are good sources of carotenoids that are important to fish coloration. Supplement the diet by soaking foods in vitamins and highly unsaturated fatty acids (HUFA). Avoid thawing foods in water because water-soluble vitamins will quickly leach from the food into the water. It is better to thaw frozen foods without water in refrigeration overnight. This will prevent important vitamins from leaching from the food. It is also a safe way to thaw the foods without encouraging the growth of bacteria on the food.

Again, knowledge is always our ally. We should always be familiar with an animal's natural diet before we purchase them. Try to immolate that natural diet as closely as possible. What does the fish eat and what is its eating style? Is the fish a grazer that eats almost continually or a predator that normally only eats a couple of times a week in the wild? Is the fish an herbivore, omnivore or carnivore? Provide a wide variety of appropriate foods for each fish. If it is a marine fish then provide it with foods that are marine in origin. Do not feed saltwater predators freshwater feeder fish.

Enhancing Immune Function

We can support healthy immune function by providing an excellent diet, immolating the natural habitat, with great water quality and reducing or eliminating potential sources of stress. Is there a more aggressive, proactive approach to enhancing immune function in fish? Actually, yes, there are some things that we can do that are most effective when used as a preventive measure.

The health benefits of garlic in our diet are well known. Studies indicate that garlic has properties that are helpful combating viral, bacterial, fungal and parasitic pathogens. Garlic also has some application for fish health management. It appears to be an appetite stimulant when added to foods and garlic has been established as helpful for controlling some types of internal parasites such as nematodes. In his study, Dr. Angelo Colorni found that garlic has some mild antibiotic action for fish (see reference at the end of this article). Many people use garlic as a treatment for combating external parasites such as Cryptocaryon irritans although the evidence for its effectiveness is anecdotal.

I personally believe that garlic is better used in prevention. It can be used to stimulate appetite, combat internal parasites and assist the animal's immune function in preventing potential disease. Garlic can be used occasionally (prior to a stressful event) by soaking the food with it. It can also be used on a daily basis for new arrivals. However, I would caution against feeding garlic on a continuous, daily basis because we do not know the long-term effects. Garlic is better used with a proactive rather than a reactive approach. Feed it to newly acquired specimens during the quarantine period and to fish that have recently been or are going to be exposed to a stressful event.

Beta glucan has proven in numerous scientific studies to be an immodulating agent that can enhance the major host defense mechanisms of the immune system. Beta glucan is a complex carbohydrate. It is safe to use with any drug or chemical and can work synergistically with antibiotics. It is known to enhance macrophage phagocytic function (the consumption of foreign invaders). As with garlic pretreatment with Beta glucan is essential.

Beta Glucan (a B-1, 3 polyglucose) and its effects on the survival of mice infected with E. coli bacteria are profound. "Survival data indicated that an approximate 97% survival in the glucan-treated group in contrast to an approximate 19% survival in the control group." In another study, pretreatment with glucan resulted in 80% survival compared to 80% mortality in control mice infected with Candida. Beta glucan has shown promise in trials against viral, fungal, parasitic and bacterial infection. At least one study used fish as the subjects of the trials.

Pretreatment with Beta glucan means that the host can activate and proliferate defense mechanisms at a faster rate than invading organisms. It can be used to avert infectious or neoplastic disease. Interestingly, it can apparently be used to stimulate host defense against fungal infections in invertebrates as well as viral and fungal infections in plants.

Beta glucan can be found (albeit may take some persistence) at some local health food stores. It is available from Source Naturals. I suggest using the 7.5mg capsules because they are pure B-1, 3 glucan. You can find out more on their website at www.sourcenaturals.com. There are many other product and information sources available on the Internet. Sprinkle some the food just prior to feeding. A little will probably go a long way. A dosage level has not been established, but Beta glucan is a food (complex carbohydrate) and not a drug or chemical. However, use some caution because too much in the way of carbohydrates is not healthy for fish. Feed it periodically to newly acquired specimens during the quarantine period. It should also be administered to fish that are obviously sick (i.e. HLLE). Beta glucan is especially helpful when used in conjunction with other therapies such as antibiotics.

Treating secondary infection

Head and Lateral Line Erosion make fish more susceptible to secondary infection by an assortment of potential pathogens. It is a good idea to examine scrapings from the lesions to look for any secondary invaders including parasites. When an active pathogen is identified the appropriate treatment or course of therapy should be implemented. Such treatments can be enhanced with the addition of Beta glucan to the diet.

Prognosis

Head and Lateral Line Erosion can cause secondary infections and osmoregulation difficulty. It may heal completely, or show no sign of remission at all. Sometimes simply moving the animal to another aquarium seems to give positive results. Moving a fish can potentially improve its environment, diet and stress level. Generally, the progression of symptoms is slow and so is recovery. It can take patience and persistence before seeing visible improvement. The response of fish treated with a variety of methods ranges from fully regaining their natural beauty to no apparent improvement at all. Oftentimes the progression of the disease is halted, but the scaring permanently remains.

Step by step

1. Improve the diet.

2. Add vitamins, Fatty acid and other food supplements to the diet.

3. Improve water quality with water changes, a quality protein skimmer and the limited use of chemical filtration pads and/or activated carbon to remove impurities.

4. Seek out and remove possible sources of stress.

5. Enhance immune function with Beta glucan and/or garlic.

6. Limit the use of activated carbon.

7. Identify and treat secondary invaders.

For further study:

"Chemical Regulation of Immunity in Veterinary Medicine" 1984, pages 443-456, The Role of Glucan in the Prevention and Modification of Microparasitic Diseases by N.R. Di Luzio, PH. D. and David L. Williams, B.S.

Histopathology of sea bass (Dicentrarchus labrax) experimentally infected with Mycobacterium marinum and treated with streptomycin and garlic (Allium sativum) extract. By Colorni A., Avtalion, R., Knibb, W., Berger, E., Colorni, B. and Timan, B. (1998) Aquaculture 160: 1-17.