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.
Hikari brand food, the package that is sold for Cichlids such as Oscars, will work well. They pretty much eat any kind of small insects and worms. Fishes such as Bluegill, Longear, and redbrest sunfish start out a zooplanktivores. They consume zooplankton until they are large enough to begin eating insects. When keeping them in captivity, they will survive well on a variety of insects that they are able to fit into their mouths. If they h ave been farm raised or fed fish food pellets in a pond then they will aslo do well eating that in an aquarium. Hikari brand food, the package that is sold for Cichlids such as Oscars, will work well. Crickets, small worms, spiders, sometimes cut up pieces of minnow They pretty much eat any kind of small insects and worms.