Unassuming, medium sized predatory fish. Mostly eat tiny minnows and eels, but has excellent out of water eyesight and senses when stalactites on the cavern ceiling above are going to fall. Then, they lure larger fish under them at just the right moment, and lay their clutch in the large predator's body to reproduce. Exceptionally patient- juice from a gland in their head can be added to tonics to make anyone who drinks them exceptionally patient and calm for 1d6 exploration turns.
Pinkish coloration around head. Bottom jaw has two 'batter' bones that can be used to crack shells and the heavy armor of other fish. One of the few fish capable of swimming up aquifers and hunting in lakes and coastal regions. Must journey back to home cavern to lay eggs in great migration.
 Helmet Fish
Have harmless sucker cups inside their mouth- jump onto bipedal creatures that pass by and wrap their mouth around their head. Since the majority are either undead, golems, or wearing helmets they often don't notice and the fish can use them to jump between different underground bodies of water. Very startling to get your head swallowed by a fish if you aren't in the above category, but not dangerous. You get +1 AC to the first attack aimed at your head with this fish on it.
 Hero Fish
Looks white or colorless like the other fish, but rubs off its scales during the mating season to reveal bright and colorful skin underneath. The fish is not special, but is rewarded as a special dinner to some underground cultures for those who commit great feats of heroism.
 Bat-Killer Fish
Fish with dark tops and long, powerful fins to jump out of the water. Can rocket out at high speeds ot ram into, and then bite and kill bats flying too close to the surface of the water. Long teeth are sometimes used to make arrowheads or the teeth of various weapons or traps for primitive cave-dwelling cultures.
These fish are uncommon and live a long time. They must dig for and insert a rough gemstone into the heads of their developing offspring, to “activate” them and have them grow to adulthood. These fish have minor magic powers, including the ability to heat a small amount of water ahead of them to boiling as a defense mechanism, or to mutate other fish into still-standing filter feeding creatures that the jewelbrain can feed off of. The blood of these fish can be used as magic ink, and their skin as leather for spellbooks or wand handles and are obviously much prized by magicians.
This fish can excrete a strange slime that allows it to 'solidify' a small amount of water on the surface of a body of water. It usually uses this to stay above the water until a predator that is hunting it goes away, but makes it vulnerable to predators out of water. Large numbers of these fish are kept and 'milked' to create oils that allow the user to walk on water, if enough is dumped into a body of water, such as from the shore or on a boat.
 Quagmire Shark
This large fish often attacks humans, drow, and other large creatures that swim in cavernous waters. They are mostly known for being able to swim and live just fine in mud as well, and whenever a mudslide happens in a village these sharks may well be among the sludge, roaming for victims.