over the weekend i was given some fresh tuna steaks so I just finished eating dinner and i look down and notice that there seems to be small thin red threads that look like blood vessels within the meat that look similar to the worms/parasites i see in freshwater fish (crappie. bass, etc. ) Is this what they are? i would really like to find out since i still have about 4 steaks that i have already grilled as we speak. thanks!