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.
When they are young they will feed on aquatic insects and small fish, as they grow they will eat crayfish, mussels and other fish. Blue catfish are considered a predator and scavenger fish. The diet of the fish usually consists primarily of live or freshly dead shad or other fish.