Mexico: up to 5 per species and 10 saltwater fish per day
5 specimens of the species per angler per day, within the limit of 10 saltwater fish
In federal waters of Mexico, recreational sport fishing allows each angler to keep up to 10 marine fish per day, no more than 5 of the same species. The picuda corvina is not among the species reserved for sport fishing (marlins, sailfish, swordfish, tarpon (sábalo), roosterfish and dorado, up to 50 nautical miles from shore, item 0.3 of the standard) and has no quota of its own. Fish over the quota must go back alive, and sport-caught fish may not be sold. From shore you need no permit; from a boat, you do (permits under the Federal Duties Law, Ley Federal de Derechos, item 4.3).
Source: Amendment to NOM-017-PESC-1994 (recreational sport fishing in federal waters of Mexico), published in the DOF on Nov 25, 2013, items 0.3, 4.3, 4.9.1, 4.9.5 and 4.11 (Sagarpa/Conapesca)
Costa Rica: minimum size 32.7 cm
327.4 mm (about 32.7 cm) total lengthconfirm with the agency
The Incopesca Board set the legal first-catch size for the picuda corvina (Cynoscion phoxocephalus, "Corvina Picuda" in the table) at 327.4 mm, equal to the first sexual maturity size given by the institute. The measure applies to all fishing activity and prohibits selling, holding, transporting or processing fish product below it. We did not confirm whether it was updated after 2017: check with Incopesca before keeping small fish.
Source: Acuerdo AJDIP/102-2017 of the Incopesca Board of Directors (session 010-2017, Feb 24, 2017), table of legal sizes at first catch