Our fish are slimy. If you’ve ever bumped one of your aquatic charges with your hand, or picked one up, you’ve noticed that layer of slime coating. Many additives that are intended to reduce stress in captive fish also claim to enhance the slime coat. Believe it or not, this coating of slime is an aquarist’s best friend. Not only does it help ward off potential parasites, it allows damaged tissue or fins to regrow. Yet many captive fish have insufficient slime coats. Why is that? What factors aid in generating an adequate mucus coating, and what can we as aquarists do to enhance this beneficial, and crucial part of our fishes’ biology? The slime coating:
If you’re a student of evolutionary biology, then it’s important to accept that somewhere along the line we evolved from fish. Life began in the sea, and over the millennia evolved to occupy land. When this took place our slime glands evolved into sweat glands, since we no longer had a direct need for mucous producing glands within our skin. Yet mucous didn’t go away altogether. If you’ve ever had a cold or respiratory infection, mucous has filled your sinuses and nasal passages, rolling down your throat and clogging up your chest. This mucous works much like a fish’s slime coat. It captures bacteria, fungus, viruses and parasites and pushes them out via sneezing or coughing, or a runny nose. For humans, the downside to this mucous defense is that it can clog up within us, giving bacteria an optimal growing condition and leading to infection. One of slime’s obvious benefits for fish is that it reduces drag by coating an irregular surface such as scales. This allows fish to slip easily, and quickly through their environment. Slime also affords fish protection from fungi, bacteria and ectoparasites. The slime coat traps the parasites and naturally sloughs them off as water moves around the fish. Within fish slime are a host of immunities, so if the parasite doesn’t slough off within the slime, there may be an antibody that kills it. While this sounds like the perfect defense mechanism, parasites evolved right beside the fish, and many have an innate ability to penetrate the slime coat and burrow into fish tissue. A slime coating also soothes a fish’s open wounds, with highly effective medicinal properties. It’s so effective in fact that human researchers are trying to isolate the active components of fish slime for use in human medicine.… More:
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