Ranitidine is a competitive, reversible inhibitor of the action of histamine at the histamine H2-receptors, including receptors on the gastric cells. Ranitidine does not lower serum Ca++ in hypercalcemic states. Ranitidine is not an anticholinergic agent.
1 The Blue Marlins have a diet of: Octopi, squid and pelagic fish such as black fin tuna and frigate mackerel.  They do prefer to hunt alone and during the day, rather than in schools, so it is safe to say they are a rather antisocial species.
Bass appear to have two effects on bluegill. First, bass simply eat a lot of sunfish helps control their numbers. Second, bass force small, vulnerable sunfish into thick weeds; but the big sunfish -- too large to be eaten by the bass -- are free to forage wherever food is most plentiful. So the presence of bass reduces the competition between small sunfish and large, thus allowing the large sunfish to grow even larger and faster.