The slime coat (mucoprotein coating) is the fish's main defenses against infection and disease. It acts as a shield against disease causing organisms in the fish's external environment.
It also acts as a barrier to prevent
loss of internal electrolytes and body fluids.
When even a small portion of the slime coating is removed, the fish will bleed electrolytes from
its body into the surrounding water.
Essential electrolytes necessary for osmoregulation are lost through breaks that may occur in the skin and slime coat, causing dangerous stress. Open wounds and abrasions caused by handling and netting are readily attacked by disease organisms, resulting in further stress and disease.
When a fish is hooked or netted, handled a placed in a stressful situation, such as low oxygen, high carbon dioxide or
temperature fluctuations, the slime coating is disturbed, making the fish vulnerable to disease, such as bacterial, fungal and parasitic
Particularly when fish are shipped in high concentrations in low volumes of water, they are subject to trauma such as being scraped,
bitten and otherwise wounded.
Ammonia, a waste product of fish's digestion and respiration, is released into the water containing
Ammonia is also released at high levels by dead fish and decaying food.
At high ammonia levels, the fish are subject to ammonia burns
which disturb the slime coating and adversely affect the fish.
Beneath the fish's mucoprotein coating (slime coat) are its scales which
can extend to the outer skin surface from the underlying dermal connective tissue. Beneath the scales in a fish's skin is the epidermis,
comprising several layers of cells. The fish epidermis is distinguished from mammalian epidermis in that mammals require hardened layers of skin
to prevent dehydration, whereas in the aquatic environment, the fish has no need for such protection. Thus, unlike the case in mammals, mitosis
is usually seen in the lower layer of the epidermal layer of a fish. Beneath the epidermis of a fish is the dermis comprising fibrous
connective tissue interspersed with black pigment cells. The vascular dermal tissue contains a network of capillaries providing nutrient to
Stress is the number one cause of a deteriorated slime coat.
Below is a list of some of the sources of stress on a fish.
Poor water quality:
Poor water quality can really eat away at the slime coat of a fish. This can come from improper pH, salinity, etc.....
The main way to avoid this is to do regular (perhaps monthly) water changes.
Water temperature is one of the most overlooked problems. While different species of fish require slightly different
water temperatures, it is important to make sure that the fluctuations in water temperature are moderate, both throughout the
day and year.
Every time you change the water in you tank, you are adding stress to the fish. This comes from both the water removal
process, and the introduction of new water that may contain chlorine and be at a different temperature than the aquarium water. Be
particularly cautious when doing larger water changes, and make sure to use de-chlorinator to treat the water.
Fish do not enjoy traveling. Transporting fish can have a drastic effect on their slime coat, and often can be a
nucleating cause of infection. When introducing new fish into your tank, take special care to acclimate the water temperature of the new fish with the aquarium.
Netting and Handling of fish:
In gathering bait this is the biggest problem you will be faced with.
Some don't are
Don't over crowd your net or holding tank without proper circulation-filtration-aeration.
Don't handle fish / bait anymore than you absolutely have to.
When harvesting, Use the proper size and quality of net to prevent the bait / fish from being gilled.
How to help your fish get their slime coat back.
(1) Aqueous aloe vera gel 5% to about 30%
(2) Sodium carboxymethyl cellulose (cmc) up to about 7.5 g/l
(g/L is an abbreviation for grams per litre : - .0265 oz per .28.16 oz)
- mucoprotein slime-replacing compound.
(3) Polyvinylpyrrolidone (pvp having
the molecular weight of about 40,000 - K-30
available from GAF Corporation) 1.3 to about 25 g/l (0.046
oz / 28.16 oz) - mucoprotein slime-replacing compound .
(4) Sodium thiosulfate or asorbic acid 12.5 (.44 oz to 2.12 oz /
28.16 oz) to about 60 g/l - dechlorinator
(5) Ethylenediaminetetraacetic acid (EDTA) 2 g/l (.07oz / 28.16 oz) -
(6) Tris(hydroxymethyl)aminomethane 0.3 to about 1 g/l ( .001 to .035 oz
/ 28.16 oz) - maintain the pH<>Diazolidinyl urea 1.3 to about 4 g/l (.05oz to 1.4 oz / 28.16 oz) -
(7) Aloe vera gel ("VERAGEL 1501") 4 liters (1.057) gallons.
(8) Sodium thiosulfate 1400 g (49.38 oz)
(9) Carboxymethyl cellulose 100 g. (3.52oz)
(10) Polyvinylpyrrolidone 400 g. (14.11)
(11) Ethylenediaminetetraacetic acid 40 g. (1.4 oz)
(12) Tris(hydroxymethyl)aminomethane 17 g. ( 0.6 oz)
(13) Diazolidinyl urea 80 g. (2.8 oz) deionized water enough to dilute to a total volume of 40 liters (10.6)