Discriminant analysis of Gut Microflora of Fathead Minnow Pimephales promelas  

The fathead minnow, an important aquaculture fish species, has been widely used in the bait fish industry and in toxicology research. The effect of diet (0 and 2% dairy-yeast prebiotic) and water hardness (Low, 35 mg CaCO₃ per L, and Moderate, 141 mg CaCo₃ per L) on general performance of fathead minnow were evaluated in concurrent 8-week feeding trials by stocking 25 fish into each of 4 replicate 110-L tanks per diet per system.  

A total of 626 identified bacterial species were found in fish raised in all four treatments combined. Mean relative percentage of gut genera with percentage greater than the average percentage of 1/626=0.16 was reported. Gut genera communities in trt1 (Basal, moderate hardness) are similar to those in trt3 (Prebiotic, moderate hardness). Seventy and fifty-seven gut genera occupied 89.52% and 88.10% in trt1 and trt3, respectively, while thirty-six gut genera occupied 81.8% and 94.17% in trt2 (Basal, low hardness) and trt4 (Probiotic, low hardness), respectively. Stepwise regularized discriminant analysis (SRDA) was performed on gut microflora. Thirty-nine out of forty-two samples were correctly classified by SRDA.