Like all other freshwater mussel species, Texas fatmucket are filter feeders that feed and survive on organic particulate matter, bacteria and algae that are filtered from the water column. Juvenile mussels live in the sediment and most likely feed interstitially rather than from the water column, using the relatively large muscular foot to sweep organic and inorganic particles found among the substrate into the shell opening.

The Texas fatmucket, like all freshwater mussels, has an interesting life history. Males release sperm into the water column, which is taken in by the female fertilizing her eggs. The developing larvae are held by the female until they mature and are ready for release. The female then attracts host fish through the use of a mantle lure mimicking fish prey of its hosts. The mature larvae, called glochidia, are released in proximity to a fish host and attach to the host’s gills or fins. Glochidia that fail to attach to a suitable host or attach to the wrong location will die. Attached glochidia encyst, or implant, into the host and develop into juvenile mussels over a period of weeks or months. Once fully developed, the juveniles excyst, meaning break away, from the host and settle on the stream bottom leaving their host relatively unharmed.

Texas fatmucket are considered to be long-term brooders, or bradytictic, and are believed to have a peak reproductive season between February and July. Four fish hosts have been reported, including: bluegill (Lepomis macrochirus), green sunfish (L. cyanellus), Guadalupe bass (Micropterus treculii) and largemouth bass (M. salmoides).

Texas fatmucket collected from the San Saba and Llano rivers have been determined to reach ages of at least 15 years. Similar to the Texas fatmucket, congeners (Lampsilis spp.) from the southeast United States were reported by Haag and Rypel in 2010 to reach a maximum age of 13 to 25 years.

The Texas fatmucket is a small to medium-sized freshwater mussel with an elliptical to sub-rhomboidal shell. The beaks are elevated above the hinge line with fine V-shaped ridges. The shell disc lacks sculpturing and has a broadly rounded posterior ridge. Pseudocardinal teeth, which are molar-like structures located near the beaks on the interior surface, are thin and compressed and lateral teeth, with two in the left valve and one on the right, are slightly curved and lamellar.

Measurements
Length: up to 4 in (100 mm)

The exterior shell with often broken black or brown rays that broaden near the margin. The interior shell surface, or nacre, is typically white, with an occasional salmon or yellow tint.

The Texas fatmucket is known to inhabit flowing streams and rivers of the Edwards Plateau, with substrates of stable sand, firm mud, stable sand and gravel bottoms. In shallower waters, they can sometimes be found in bedrock fissures or among roots of bald cypress and other aquatic vegetation.