Simple Summary The bala shark Balantiocheilos melanopterus does not reproduce naturally under culture conditions, and hormone stimulation is routinely administered to male broodstock to ensure production of adequate quantities of high-quality sperm. Poly(lactic-co-glycolic acid) (PLGA) microparticles with slow release of 10 mu g/kg fish body weight GnRHa were injected to induce spermiation in bala sharks and to compare them with standard treatments in tropical cyprinid culture: recombinant hCG and GnRHa with metoclopramide. The PLGA microparticle treatment led to significantly higher plasma T and 11-KT concentrations at 24 h post-injection than was detected in the control group. Sperm motility parameters were evaluated during the 10-60 s after motility activation at 2 s intervals. Starting from 28 s post-activation, the motility percentage was significantly higher in the PLGA group compared to the control group. The PLGA microparticle treatment was also found to significantly increase sperm volume and total sperm count compared to control (0.9% NaCl). The PLGA microparticle system with continuous release of GnRHa was identified as optimal for inducing spermiation in cyprinid bala sharks. Hormone treatments are routinely employed with bala shark Balantiocheilos melanopterus male broodstock to stimulate the production of high-quality sperm. In the current trial, three spermiation-inducing treatments were evaluated: 20 mu g/kg body weight (BW) recombinant hCG; 20 mu g/kg BW [D-Ala(6), Pro(9), NEt]- gonadotropin-releasing hormone (GnRHa) with 20 mg/kg BW metoclopramide; and poly(lactic-co-glycolic acid) (PLGA) microparticles with slow release of 10 mu g/kg BW GnRHa. A 0.9% saline AS negative control was also included. Administration of the GnRHa through the form of slow release of PLGA microparticles 24 h after treatment resulted in a significantly higher sperm volume, motility percentage, and total sperm count compared to the control. Injection of GnRHa with metoclopramide induced sperm parameters that did not differ from the control, with the exception of motility percentage. The lowest potency to induce spermiation in bala sharks was in the treatment with recombinant hCG. Both PLGA microparticles and GnRHa with metoclopramide significantly increased blood plasma concentrations of testosterone and 11-ketotestosterone compared to the control. The PLGA microparticle system with continuous release of 10 mu g/kg BW GnRHa was the most effective treatment in inducing spermiation in bala sharks.