Some central American cichlids especially riverine species like Theraps Lentigosum, Thorichthys from the helleri group yellow labridens etc can develop problems if fed too much bloodworm. All these fish have reported to be susceptible to bloat issues.
I am told bloodworm alone will not cause bloat as bloat is said to be triggered from stress.
I know lots of hobbyists that have kept these more delicate centrals that have lost fish to bloat type symptoms after a feeding regime using bloodworm.
I don't know the exact science behind all this but I never feed it my centrals as a precaution.