A cargo ship is attacked by strange fish under the command of Harry Black, modern-day pirate! Aquaman and Aqualad arrive, but nothing they do can get past the fantastic creatures. Aquaman gets suspicious after seeing seaweed float onto one of Black's fishes, and manages to get through Black's defenses with a whale and some hammerhead sharks. He then explains to an amazed Aqualad that when the seaweed floated into the fish's face, it didn't try to shake it off, so Aquaman figured Black's fish were robots. He distracted Black and had some electric eels short circuit the control panel.
Short, sweet, and to the point. These classic stories are missing continuity and character development, but they are great little self-contained stories with fantastic artwork and decent plotting. You can't do much in six pages, but the writers of the Silver Age managed to get more into six pages than most modern writers can in 22.
The buzz-saw fish is amusing, as is the fish that shoots out corks to disable Aquaman's swordfish. It's actually fairly obvious from the start that Black's fish aren't real, but even then Aquaman has to manage to get around them. The designs on the fantastic fish are very nice, and they work well visually.
I don't know if Nick Cardy inked his own work on this story, or if he had an inker, but the inking seems a little heavy at times. On the third page, in the first panel, both Aquaman and Aqualad have heavy accents around their faces. Aqualad tends to look a little strange in these early stories. There are times I think Nick isn't quite sure what a little boy should look like.
Another good story from the Silver Age.