Coldwater Marine Aquatics recommends you keep these animals in 55F-60F water.
The penpoint gunnel (Apodichthys flavidus) is a gunnel (Pholidae) of the Pacific coast found from Kodiak Island in the Gulf of Alaska to Santa Barbara Island in southern California.
The penpoint gunnel varies in shades of green, maroon, or brown. It is commonly 4–8 inches, though it can be up to 1½ ft. It most easily distinguished by the dark bar below each eye, as it is commonly found peeking out of a kelp bed or crevice. However, if you are lucky enough to see the entire gunnel, there is a row of dark and/or pale spots along the midbody and commonly a series of short, pale bar-like marking extending down from the top of the dorsal fin. The first spine of the anal fin is large and grooved like a fountain pen point. It has a continuous dorsal, tail and anal fins, but no ventral fins. The tail is defined by slightly longer rays. The anal fin is about half the length of the dorsal fin.
The penpoint gunnel is found in intertidal areas (0–60 ft). It can sometimes be seen in tide pools, also in eelgrass beds, sea lettuce beds, and in stands of kelp. It commonly takes on the color of the vegetation it inhabits. If there is no vegetation (in winter, for example), it can also inhabit rocky areas, lurking under rocks and in protective crevices. However, it can also remain out of the water under rocks or seaweeds. The penpoint gunnel can breathe air when out of water.
Penpoint gunnels feed on small crustaceans and mollusks. Pairs are found coiled around egg masses.