El-Fish

A hint on how to create some really weird mutations and have fun doing so :

El-Fish stores its fish as roe in binary files.
When you click on Restore, the software converts a roe file back into a fish. But you can also convert almost any binary or ASCII File (a customer database, a budget spreadsheet, a health-benefits memo) into a fish.

Just copy the file with new extension .ROE.
(Don't use EXE or COM Files.)

After loading El-Fish, Click on Restore From and find the fishy new file.
It will create one or more mutant aquatic life forms.

I tried a file containing Earned Run Average statistics for American League pitchers, and as expected, the fish created was extremely ugly. (Information from Cheat Machine)