You make the bump thread yourself or if your lazy get someone else to make it for you. Basically it's just a thread that people can bump when you are glowing, so you can get more plays and people see oh hey there is a tank glowing. Normally it's best to put it in the Signature along with your tank, so people can bump it easily.
If you are applying for a certain section then you need at least 14 fish of that type of section. So if you were applying for dolphins then you need at least 14 dolphins whether they are regular dolphins or irrawady ones. If you are applying for the monster section then you will need at least 14 monsters.
Now you will need to have high trigger fish for more people to play it. High Trigger are mainly Airsharks, Lawnsharks, Dolphins (both kinds), Grunny Sub (both kinds). And others, but I forget those off the top of my head.