OSLO, Aug 1 (Reuters) - China Fishery Group CNFG.SI raised its stake in Peruvian fish feed maker Copeinca COPE.OL to 97.7 percent through a voluntary takeover offer, the firm said on Thursday. China Fishery pursued Oslo-listed Copeinca, currently worth $820 million, for months, and won the battle after Norway's Cermaq CEQ.OL was forced to withdraw when minority shareholders revolted. (Reporting by Balazs Koranyi) ((Balazs.Koranyi@thomsonreuters.com)(+47 22 93 69 62)(Reuters Messaging: balazs.koranyi.thomsonreuters.com@reuters.net)) Keywords: CHINAFISHERY COPEINCA/TAKEOVER