User blog comment:D2r/Unanswered Questions of Redwall/@comment-1421927-20100125010712

They seem to eat fish sparingly; if fish were swept into Lake Kotir and unable to get out, they could have reproduced, made more fish, which reproduced and so on. If they are only eating one-two fish a season, and if the fish are laying thousands of eggs, they might be dealing with over population of fish rather than an under population.