We spend a lot of time pining over and dreaming about fish we will likely never own, and maybe even never see. But there’s a whole world of wild and crazy fish that we know about, but which we know no one will ever see alive again.
There is a fascination with ancient fish, which is the general public is so interested by fish like Coelacanth. There’s a whole subculture of freshwater aquarists interested in ‘ancient’ fish for aquariums like Arowanas, Lungfish, Gars and the like.
But one group of fish which would have made the best (and worst) aquarium fish are likely the Placoderms. These bony plated fish are very different from the ray-finned bony fish and cartilaginous sharks and rays which still live today.
The placoderms including Dunkleosteus are the true dinosaurs of fishes with massive armor and huge spiny jaws. Many other aspects of their anatomy is so alien to us today that we might hardly recognize them as fish at all, were it not for them swimming around in watery habitats.
Alas these terror fishes are long since gone and until someone finds another population of living fossils like we did with the Coelacanth, we can only enjoy and admire their fossils across eons of time.