Scanner 101 question

The Java documentation contains this simple Scanner example:
String input = "1 fish 2 fish red fish blue fish";
Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*");
System.out.println(s.nextInt());
System.out.println(s.nextInt());
System.out.println(s.next());
System.out.println(s.next());
s.close();


I'm having trouble understanding this expression: ("\\s*fish\\s*").
At first I thought this was some type of regular expression, but then I read the next example, which says: " The same output can be generated with this code, which uses a regular expression to parse all four tokens at once," the phrasing of which implies that the above example doesn't use a regular expression.

I'm sorry this is so basic, I just don't understand it from the Java documentation.
1)Does this line actually use a regular expression:
Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*");
2) If so, could someone tell me how it's read? I know there are tutorials available, but I know if someone could just walk me through this one example, I could pick up the rest on my own. I'm just finding this particular example confusing because I don't understand how that sequence of characters works.