Occult haemoglobin in fish skin mucus as an indicator of early stress

Abstract

Early induced stress may result in the release of free haemoglobin into the skin mucus of teleostean fishes. If this were the case, it could be indicated quickly and simply by the colour change of a commercially available haemoglobin test strip. Preliminary tests on Mugil cephalus (grey mullet) encouraged more extensive investigations with Chanos chaaos (milkfish), Caranx ignobilis (papio), Albula vulpes (bonefish), and Chaetodon miliaris (butterfly fish). The results indicated that unstressed individuals of these species have no detectable haemoglobin in their skin mucus but, within 2-4 min, the pigment will appear in occult amounts if stress is applied. Additional studies confirmed that it was haemoglobin and no other possible contaminants in the mucus which caused the colour change of the test strip.The technique is simple and quick, and is itself harmless to the fish. It is of immediate potential value to fish culturists for the detection of early stress conditions. Efforts can then be made to lessen or remove the stress conditions before debility and possibly overt disease take over. A further application of the technique may be the identification of individuals genetically better able to resist disease.

Effects of contaminated sediment on the epidermis of mummichog, Fundulus heteroclitus

“…On subsequent sampling days (days 3, 7, and 13), three US and three CS aquaria were chosen at random and the fish therein processed. The fish were removed from the aquaria and Hema‐combistix® Hb test strips (Ames, Elkhart, IN, USA) were applied directly to the mucus‐covered skin, one on each side of the caudal peduncle [20]. These strips develop in 60 s and have a sensitivity of 0.15 to 0.62 mg Hb/L, graded colorimetrically.…”

“…Hemorrhage often accompanies tissue injury and inflammation. Red blood cells may lyse, releasing free hemoglobin (Hb), which can migrate from the inflamed tissue to the mucus [11].…”

Interaction of Escherichia coli O157:H7 E318 cells with the mucus of harvested channel catfish (Ictalurus punctatus)

“…However, mucus may lose its antibacterial activity soon after the fish is slaughtered. Certain inhibitors in blood serum greatly reduced the antibacterial activity of fish mucus (Hjelmeland, Christie, & Raa, 1983;Smith & Ramos, 1976) as fish skin could easily be contaminated with blood during processing. Proteases present in mucus could also inactivate the antibacterial compounds in fish mucus (Robinette et al, 1998).…”

Parent-touching behavior by young fishes: incidence, function and causation

“…Also, handling of fishes causes a significant increase of superficial mucous cells in the epidermis (Pickering & Macey 1977), but it is not yet clear whether this results from physical contact with the epidermis or from a more general physiological stress. Physical stress (handling) has been shown to cause a release of free haemoglobin into the skin mucus within a few minutes (Smith & Ramos 1976).…”