The problem is clearly that you've picked too "cool" an animal for your nickname. I reckon you'd be fine if you went for something slightly more low profile. i.e.
Dormouse, Shrew, Kitten, Ladybird, Woodlouse, Seagull, Goose, Moth, Pubic Louse, Guinea Pig, Bee, Crane Fly, Giant Panda, Hedgehog, Pheasant, Meerkat, Squirrel, Swan, Parrot, Chicken, Giraffe, Gerbil, Sloth, Slow Loris, Platypus.
These animals are sufficiently shit to suggest that the names would be available.