It really depends on the type of shots you want to get. The lenses you mention are good ones, but like all glass they have to be used within their respective limitations. I have a Nikon 70-300 and it has produced some exceptional results for me — but neither the 18-55 nor the 70-300 are considered “fast” glass for use in lower light conditions.
I own the Tokina 12-24, and it’s a top notch wide angle. Wides produce a certain exaggerated perspective that can be a lot of fun to play with. Just keep in mind that the 12-24mm focal length is meant for broad landscapes and exaggerated foregrounds.
I have actually done a lot of my fish photography this year on the 35mm f/1.8 ($199). It’s got a very large aperture, which allows it to produce sharp images in the early morning and late evening hours when fish are often caught. It’s small, light, and very sharp.
Shot from the Tokina 12-24:

Shot from the 35mm:
