not to stir up the FA controversy but... perhaps the differing opinions in regard to the consumption in FA are due to the differences in fish anatomy. As per the FAO (Food and Agriculture Organization), there are 4 different gut configurations: a straight stomach with an enlarged lumen (for example, the Esox family), a U-shaped stomach with an enlarged lumen, a Y-shaped stomach with a cecum formed by the “stem”of the Y, and those without a stomach in which the midgut attaches directly to the esophagus (cyprinids – includes both carp and golden shiners). Note that in some families, only one specific genus will lack a stomach. Stomachless fish (which do not produce pepsin) tend to be herbivores or omnivores, while the first 3 classifications (those with true stomachs) are typically carnivores which rely on peptic digestion.
Carp and other Cyprinids (GSH, Blennies, etc.) do not have a stomach and do not produce pepsin (they rely on trypsin). They digest their food by grinding the plant material (interdigital teeth) before swallowing, exposing more surface area to the digestive enzymes. Large quantities of plant material are required as it is believed that only 5-15% of the material is digestible – the rest (plant fiber) passing through as fecal material. Unlike fish with stomachs, pepsin is not produced, but rather trypsin is the main protease excreted. Lipolytic activity has been observed in carp and there are ongoing studies into carbohydrases and collagenase. Interestingly, amylase (the enzyme which breaks down starch) has been found in both goldfish and bluegill but not LMB. The presence of other enzymes have been postulated but not yet isolated. To quote FAO: “Much remains to be learned about intestinal digestion in fish”. Some interesting reading which verifies the above info:
http://www.fao.org/docrep/X5738E/x5738e02.htm#6.3%20common%20carp%20%28cyprinus%20carpio%29
John’s post and others’ observations and anecdotal evidence are what I find great about this forum. Rather than dismissing their (and my own) observations out of hand, it led me to do further research…. confirming that cyprinids including GSH do have the capability to digest FA.
