Aquatic animals commonly sense flow using superficial neuromasts (SNs), which are receptors that extend from the body's surface. The lateral line of fishes is unique among these systems because it additionally possesses receptors, the canal neuromasts (CNs), that are recessed within a channel. The lateral line has inspired the development of engineered sensors and concepts in the analysis of flow fields for submersible navigation. The biophysics of CNs are known to be different from the SNs and thereby offer a distinct submodality. However, it is generally unclear whether CNs play a distinct role in behavior. We therefore tested whether CNs enhance foraging in the dark by zebrafish (Danio rerio), a behavior that we elicited with a vibrating rod. We found that juvenile fish, which have only SNs, bite at this rod at about one-third the rate and from as little as one-third the distance of adults for a high-frequency stimulus (50 < f < 100 Hz). We used novel techniques for manipulating the lateral line in adults to find that CNs offered only a modest benefit at a lower frequency (20 Hz) and that foraging was mediated entirely by cranial neuromasts. Consistent with our behavioral results, biophysical models predicted CNs to be more than an order of magnitude more sensitive than SNs at high frequencies. This enhancement helps to overcome the rapid spatial decay in high-frequency components in the flow around the stimulus. These findings contrast what has been previously established for fishes that are at least ten-times the length of zebrafish, which use trunk CNs to localize prey. Therefore, CNs generally enhance foraging, but in a manner that varies with the size of the fish and its prey. These results have the potential to improve our understanding of flow sensing in aquatic animals and engineered systems.

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After a priming with the combination consisted of 13.3 ug of [D-Ala6, Pro9 Net] - mGnRH (LRH-A, China) and 2 mg of Domperidone (Dom; Motilium-M, Jannsen, Thailand) per kg female, the resolving doses of 17α,20β-dihydroprogesterone (3; 4; 5mg/kg), Progesterone (10; 15; 20mg/kg) and Desoxycorticosteron acetat (7,5; 10; 15 mg/kg) for oocyte maturation and ovulation in vivo on a Grass carp (Ctenopharyngodon idellus) were tested. Results of the study indicated that optimal doses of 17,20; P and DOCA were 4; 20 and 10 mg/kg respectively. Result of oocyte maturation and ovulation in vivo of the fish by the optimal doses of the abovementioned steroid hormones mixed with LRH-A+Dom or Dom in a single injection brought low spontaneous spawn rate, however their fertilization and hatching rate were normal and quite satisfy the requirements of fish artificial propagation techniques.