(FORTUNE Magazine) – Banks will go to almost any length to collect bad debts, and First Interstate Bancorp is no exception. To pare down the $90 million in shaky loans it has made to Peru, the Los Angeles-based concern is about to turn fishmonger. Through its trading arm, First Interstate Trading Co., the bank plans to peddle Peruvian products from shrimp to asparagus in the U.S. and abroad. It will keep $1 for every $3 of sales. Ken Rosenberg, president of the trading company, hopes the deal will net First Interstate $40 million over five years. The bulk of Peru's remaining debt to the bank, $50 million, will have to be rescheduled, like most loans to Latin America. A recent reshuffling of Peru's cabinet has delayed formal approval, but Rosenberg says, ''We have reached an agreement. It's just a question of finalizing everything.'' Since Congress passed enabling legislation five years ago, some 40 banks have received permission to set up trading companies that must get over half their revenues from exporting U.S. products. About a dozen banks found the business so vexing that they quickly got out. But several others, among them Chase Manhattan and Manufacturers Hanover, have developed active trading subsidiaries. With U.S. bank loans to Latin America now around $80 billion, they will be watching First Interstate's experiment closely.