Experimental fish is finicky

Last week I switched from fish flakes to floating pellet food. The two control fish eat them, and the first experimental fish also. The second experimental fish avoids them. I'm wondering if they are too large or have a different bad taste. I tried cutting them into smaller pieces, but I didn't wait around long enough to witness him eating them The pellets soak up the TSB with Lactobacillus very well compared with the flakes.

I had various growth on my MRS plates when I inoculated them with fish feces. I need to rule out the species with endospores. The remaining species won't be Lactobacillus, unless it was endogenous. I'm wondering if I should simplify my experiment as isolation is proving difficult with wild samples.

 In the mean time I made quite a bit of TSB. It's stored in our fridge and available to anyone who needs it. I learned (flip a switch and set a dial) how to use the aliquot machine to dispense it into vials.