Stalking catfish had scales of a gleaming metallic green color. Their whiskers reached 12 inches (30 centimeters) long and their bodies reached 30 feet (910 centimeters).
This fish moved slowly between underground pools of water meticulously and methodically feeling everything within reach with its monstrous barbels.
Like their top-world relatives, these giants were solitary animals throughout most of the year. Annually, stalking catfish gathered in large bodies of water for a whole week for the breeding season. An average breeding pool could contain up to a dozen of these fish at a time. During that time of the year, the surrounding species' populations were greatly reduced due to the stalking catfishes' appetite. After the breeding season was over, the females laid up to a hundred eggs out of which only four or five survived to maturity.
When trying to hide from stalking catfish, using concealing magic was virtually useless if one was within the barbels' reach. Once the whiskers touched anything edible, the electric impulse shot into the fish's simple brain made it blindly and instinctively lunge forward and swallow the prey whole.
Stalking catfishes were virtually blind and fully dependent on their barbels to hunt and fight. If the whiskers were severed, it left the giant fish helpless and vulnerable to bigger predators in the darkness of the Underdark caverns. However, trying to sever the barbels was dangerous, especially if attempting to cut them at the whiskers' base—it was like announcing the presence of prey loudly and clearly just a couple of feet away from the animal's gaping mouth.
The stalking catfish was a very adaptable predatory species. Unlike their ordinary and giant brethren, they were able to spend almost all their time out of the water. These catfish were able to move about on the ground using their powerful fins. This enabled them to freely migrate between underground pools and lakes in search of untapped feeding areas after depleting their previous habitats.
Owing to their adaptability, these creatures were on occasion known to move to the surface world. When that happened, the stalking catfish inevitably became the apex predator of the area unless something bigger and hungrier was already there, like a dragon. Underground, a stalking catfish was only one of a number of giant carnivores fighting for territory. Tunnelmouth dwellers were the most common predator feeding on stalking catfishes. Tunnelmouth dwellers would ambush the catfish and work their jaws until the stalking catfish was ripped in halves simply because they couldn't swallow giant catfish whole.
Even though extremely dangerous, stalking catfish were delicious. Its meat was cooked, smoked, or sold raw for as much as 10 gp per pound in almost any market. Their eggs went for 6 gp per dozen (the eggs needed to be kept submerged in water before use). The eggs often were cooked into 'catfish egg cakes', a flavorful exquisite savory bite-sized delicacy that was valued at 20 gp per cake. The stalking catfish's green shimmering hides were sought after for their beauty and often used to craft very fashionable +2 scale armor. The barbells were cut down to foot-long pieces and encased in amber to create a wand of enemy detection (only one wand could be crafted per fish).
- Venom in Her Veins (mentioned)