Yellow Bullheads are traditionally found in the clear, warm waters of low gradient streams with permanent flows and rocky bottoms or the shallow weedy bays of lakes but this habitat is not common in California, thus limiting their distribution. When they are found in the state it is most often in clear weedy backwaters and canals. These areas often have less than optimal environmental conditions but Yellow Bullheads are capable of surviving in dissolved oxygen levels lower than 1 mg/L and in temperatures as high as 37-38°C making them well suited for such harsh conditions. They are an omnivorous species feeding mainly at night on aquatic insects, mollusks, crayfish and other crustaceans, and fish.
Spawning usually begins in May and can continue through to July. Both males and females will work to clear a depression into the bottom and occasionally under debris or in the entrances to abandoned muskrat burrows. A female will lay between 300 and 700 eggs in a nest at one time and can lay between 1,600 and 4,200 in a single season. The eggs hatch 5-10 days later and are protected by their parents until they reach approximately 50 mm in length. A year later they will average 53 mm in length and by age 5 they will average 42 cm long.
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