The black and white picture separated most fish into 2 or 3 stripes. As an estimate I took the results and divided by 2. The result from Image J was 659 individual strips so I estimate about 330 fish.
Slice | Count | Total Area | Average Size | Area Fraction | Mean |
tropical fish.jpg | 659 | 178569 | 270.97 | 9.3 | 254.447- |
The image was downloaded from http://thundafunda.com/33/underwater-animals-fish/School%20of%20Tropical%20Fish,%20Tahiti%20pictures%20underwater%20photos.php