I apologise for being an ichthyological pedant, but you were right to call these gars: they are not garfish, which are quite different. The cichlid top right is an Oscar, I think that the other cichlids are some type of Geophagus.
@gentle lemur You are not being a pedant, you are rightfully correcting what is after all a taxonomical mistake. Thank you for correcting, I should have more diligent and ought to have checked if garfish wasn't something totally different than gar, as it turned out to be.
Thank you also for identifying the other cichlid at least to the genus level. Zootierliste lists Sven's eartheater, Geophagus sveni, for the Rotterdam Zoo (one of four holders listed).
@gentle lemur That means it's kind of a remarkable species to have in zoo I guess. Unfortunately this species is unsigned and has no information whatsoever at the exhibit, so I kind of overlooked them and didn't try to get a shot of the cichlids. If I'd known I would have. That said, I'll probably be returning to the Rotterdam Zoo at some point so I'll sure try when I do.