Pond Boss Forums INTRO Questions & Observations Slime time!

A rather intense discussion about proper fish handling on another thread spurred my curiosity about the topic of ... fish slime. I recall reading an account of fish mortality caused by handling with dry hands, which strips off the protective slime and increases risk of infection. In fact, I try to encourage anglers to get their hands wet before picking up a large fish, if at all possible.

But I don't recall seeing slime protection much mentioned in handling at all. Is it actually worthwhile? Anybody know?

Yes always wet your hands before handling a fish. Removing the slime coat by touching with dry hands causes the touched area to become suspectable to infection.

Pharmaceutical and Biosciences Journal - Volume 11, Issue 1, January-February 2023
Catfish (Clarias gariepinus) Slime Coat Possesses Antimicrobial and Wound Healing Activities
Abstract
The mucoprotein slime coat often found on fish bodies act as defense against invasion by microbes and other environmental dangers. There is an increase in the incidence and emergence of multidrug resistant microbial strains, which has necessitated the need for newer antimicrobial agents. With this background, the aim of this study is therefore, to assess the antimicrobial effects as well as wound healing properties of mucin isolated from a catfish slime coat. Collection, precipitation with 96% absolute acetone, isolation and preparation of the mucilage from the slime coat of a live catfish was performed to obtain the powdered mucilage or catfish mucin (CM). The antimicrobial effect of the CM was evaluated using the agar dilution technique, and the minimum inhibitory concentration (MIC) were determined against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomona aeruginosa, Salmonella typhi, Klebsiella pneumonia, Candida albicans and Aspergillus niger. The wound healing effect of CM was also studied using wound healing excision model in rats. In addition quantitative biochemical analysis of the constituents of the catfish mucin was also performed using standard procedures. The CM exhibited antibacterial activity against Bacillus subtilis, Klebsiella pneumonia, Salmonella typhi, Staphylococcus aureus and Escherichia coli with an MIC value of 3.0, 3.0, 5.0, 6.0 and 6.0 (all in mg/ml) respectively, with no appreciable activity against Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Biochemical analysis of CM showed the presence of carbohydrates (76.31%), moisture content (10.86%), proteins (7.38%), ash (2.34%), fibre (2.06%) and fats (1.06%) per 100 mg of the mucin. While wound healing study showed that CM reduced wound diameter and increased the rate of epithelialization in the increasing order of 40%, 10% and 20% preparations compared to penicillin G, a standard agent. In conclusion, the catfish mucin, a glycoprotein from the slime coat, exhibited antibacterial activity with bactericidal potentials and possesses wound healing properties.


From 2 sources
Fish culture operations, public aquariums, fish biologists and aquatic researchers often have the need to transport live fish. These fish are frequently transported in live-haul boxes by ground transportation. Activities involved with transporting fish, such as handling, confinement and exposure to sub-optimal water quality, have the potential to create physiological changes in the fish because of increased stress. Because of the affiliation between stress and fish health, it is important to minimize the amount of potential stressors as well as to minimize the duration of exposure to stressors during these procedures. Furthermore, understanding aberrant environmental conditions and how they affect fish often leads to establishing new protocols that reduce stress. Increased survival rates and the arrival of healthy fish are dependent on transport and on the pre-handling and post-handling procedures associated with fish-hauling operations.

Handling While many mammalian species adapt to handling, most aquatic species do not. Handling is both physically and physiologically hard on the animals. Many aquatic species have a slime coat that protects their skin from bacteria and parasites. Handling usually disrupts the integrity of the slime coat, leaving the animal susceptible to disease. It also induces the fight or flight response during which a quick release of hormones begins a rapid metabolism of sugars and a rise in blood sugar. Blood pressure, heart rate, and respiration all increase, and digestion may temporarily cease. These reactions normally initiate an inflammatory reaction which is suppressed in fish by an adrenalin release. Peculiar to fish is the regulation of water into and out of the body during flight or flight response. Under stress, freshwater fish absorb too much water and saltwater fish lose too much. The rapid metabolism of sugar reserves provides additional energy to overcome this fluid imbalance.9 In addition, most handling requires the animal to be removed from the water; for some, just the atmospheric pressure can be damaging.

Trout guides will refuse to take a picture of you holding the fish unless your hands are wet. Quick pic, then back in the water.

Thanks for the responses. We know that stress is bad for human health, so no real surprise the same is true for fish.

I seem to remember that Middle Eastern fishermen would smear the slime of saltwater catfish on skin wounds to help the healing process. That would be in accord with the research mentioned by ewest.