That's a remarkable number of gross FCR for an adult LMB. The koi results are a little better than I estimated for carp which comes in about 6 for a 1 lb LMB growing to 3 lbs in 180 days. I wonder if the koi are possibly more energy dense than carp or perhaps some of the koi fed in the brood ponds manage to grow before being eaten. Do they feed forage daily, weekly, monthly?

Yes, I agree that length isn't what converts so I always use standard weights when estimating prospective scenarios. The question of length I think is important from the perspective of a predator's realized consumption. A predator can consume a variety of different sizes but what is it going to consume? Would what it consumes most be most optimum? If not, why would what it consumes most be less optimum?

Fishing with my son the other day we fished with a 4 1/2" BG and a 18" LMB seemed very interested. He chased it multiple times but never got his mouth on it. After about 10 minutes of this we fished for a different bait ... a 3 in BG ... and the 18" LMB took it within 10 seconds and the fight was on. I know the LMB could have eaten the 4 1/2" BG. It was, like the 3" one, struggling and obviously distressed and vulnerable. Yet the 18" LMB seemed cautious about taking the larger bait. At standard weight, the larger BG would be 4 times as heavy as the 3". The 3" BG is only 1/6 the length of an 18" LMB yet two of them is almost enough energy to sustain the 18" LMB for a day(assuming standard weights for BG and LMB). With three of them every day for 180 days it can double in weight (even though the FCR isn't that great 11.94). In a typical pond, getting 3 meals of 1/6 BG prey everyday for 180 days must not happen very often for LMB that are 18" long.