Subterranean Fish

Three kinds of underground fish cause special trouble in the waterways of deep dungeon complexes, especially where an underground forest's streams and a great subterranean river wind through the caverns. They prefer water lit by glowing lichen or similar light. All crave flesh and, when hungry, go after anything rat-sized or larger, even bigger than themselves; recently fed, they are docile.

These nearly round, lacy-finned fish, one to three inches thick, sport vivid green, blue or brown stripes, with rare solid blue or green specimens. The cleverest of the three, they swim in schools of 10 to 40 behind a large old leader whose bite deals 1-4, merging at night into groups of up to 300. Each eats its own weight every three days, and the school brings down big prey together. A bite automatically paralyzes creatures of 2 HD or less; tougher ones must save vs. poison against every bite or black out for 3d6 rounds, less one round per Hit Die. Waders who suddenly float helpless often drown.

Pairs mate for life and spawn 10-100 eggs four times a year, with 10d4 surviving. Drow, duergar and lemon fish eat them, and travelers net them after sating a school with meat. The flesh is delicious, organs make paralytic poisons and salves, scales decorate jewelry and clothing, and live fish fetch 2-12 gp from wealthy pond owners, though they last only 2-4 years in captivity against 15 in the wild. Eggs bring up to 1,600 gp a pound (about 800 eggs). They swallow shiny trinkets, and 1 in 20 holds a small valuable that must be cut out.

Golden-yellow with black-tipped fins, these fierce predators look like living coins, and their dorsal fin breaks the surface like a shark's. The tail is armed with yellow and black barbs and a slim spike up to 2 feet long, and the black saucer eyes close as they strike. Adults run 2 to 6 feet, the strongest growing largest. Each round one bites with twin rows of teeth, up to 2d8 for the biggest, and tail-slaps for damage equal to its HD; the slap's poison then deals 1d6 a round for as many rounds as it has HD unless the victim saves vs. poison. If its body is punctured, it releases a cloud twice its length across; those inside are stunned 1d4 rounds unless they save vs. poison, which they do at -4, and immune companions attack them while the wounded fish escapes.

They swim alone or in threes at most, usually 7 HD or less, the largest always alone. The flesh is tough, but drow and duergar love the organs, harmless after death. Females spawn up to four times yearly, 100-600 eggs each, and 10% of young survive; a pound of eggs, roughly 600, can bring 400 gp.

Sleek, barracuda-shaped and half a foot to 2 feet long, plecos glide over shallow beds in schools of ten to a hundred, sparkling like strings of diamonds and luring many to their deaths. The bite only grips, but barbels under the chin stab for 1 point and inject venom. A victim saving vs. poison at -4 is unharmed; otherwise a wasting sickness sets in within two hours, draining 1 point each of Strength and Constitution daily until one hits 0. A cure works within 72 hours; afterward the victim withers away. Plecos attack only in self-defense and scavenge rot, which may explain their potent venom and foul, inedible flesh. Their shine fades at death, so only their eggs are worth anything, to assassins who brew a crippling poison from them.