In Angular, I need to search objects in an array

You can use the existing $filter service. I updated the fiddle above http://jsfiddle.net/gbW8Z/12/

 $scope.showdetails = function(fish_id) {
     var found = $filter('filter')($scope.fish, {id: fish_id}, true);
     if (found.length) {
         $scope.selected = JSON.stringify(found[0]);
     } else {
         $scope.selected = 'Not found';
     }
 }

Angular documentation is here http://docs.angularjs.org/api/ng.filter:filter

To add to @migontech's answer and also his address his comment that you could "probably make it more generic", here's a way to do it. The below will allow you to search by any property:

.filter('getByProperty', function() {
    return function(propertyName, propertyValue, collection) {
        var i=0, len=collection.length;
        for (; i<len; i++) {
            if (collection[i][propertyName] == +propertyValue) {
                return collection[i];
            }
        }
        return null;
    }
});

The call to filter would then become:

var found = $filter('getByProperty')('id', fish_id, $scope.fish);

Note, I removed the unary(+) operator to allow for string-based matches...

I know if that can help you a bit.

Here is something I tried to simulate for you.

Checkout the jsFiddle ;)

http://jsfiddle.net/migontech/gbW8Z/5/

Created a filter that you also can use in 'ng-repeat'

app.filter('getById', function() {
  return function(input, id) {
    var i=0, len=input.length;
    for (; i<len; i++) {
      if (+input[i].id == +id) {
        return input[i];
      }
    }
    return null;
  }
});

Usage in controller:

app.controller('SomeController', ['$scope', '$filter', function($scope, $filter) {
     $scope.fish = [{category:'freshwater', id:'1', name: 'trout', more:'false'},  {category:'freshwater', id:'2', name:'bass', more:'false'}]

     $scope.showdetails = function(fish_id){
         var found = $filter('getById')($scope.fish, fish_id);
         console.log(found);
         $scope.selected = JSON.stringify(found);
     }
}]);

If there are any questions just let me know.