Final answer:
The sentence provided by the student is a run-on sentence because it contains two independent clauses that are improperly connected without correct punctuation or conjunction. It can be corrected by inserting a comma and the coordinating conjunction 'but' between the clauses.
Step-by-step explanation:
The student has asked to identify the type of a specific sentence. The sentence in question is: 'Two kinds of fish native to this area are endangered, many more are threatened. This is a ___ sentence.' This type of sentence is classified as a run-on sentence because it consists of two independent clauses that are incorrectly joined without the appropriate punctuation or coordinating conjunction.
To correct a run-on sentence, it can be revised by using proper punctuation and conjunctions. For example, this run-on sentence can be corrected by writing it as: 'Two kinds of fish native to this area are endangered, but many more are threatened.'