Simplify the following text for a Grade 9 native English-speaking person.
Original: Many fish such as sharks , rays and catfishes can detect electric fields , and are thus electroreceptive , but as they can not generate an electric field they are not classified as electric fish .
Simplified: Many fish , for example sharks , rays , and catfishes are electroreceptive . They can not generate electric fields though , and are therefore not classified as electric fish .