Even when I hear about your app, I feel like going to fish ! The concept behind is really interesting, Multiple benefits can be obtained : for environment protection, people culture, fishermen pleasure and responsability, ...
I've worked on a few multiplatform apps, including Android, IPhone, tablets etc using Phonegap and HTML5 for an easier targeting of different OS. I plan to use it again if you choose me. A photo of the fish will be taken and then scanned with all the effects you recommended, then the info will be displayed. Another choice is to upload a photo to the phone or tablet or on the contrary download it and then scan for fish.
Besides all you've asked for, which is rather clear, I propose to add fun by building quizzes of already scanned fishes and building some "serious" game ? Since the data will already be there, this can make the app more enjoyable.
The development will take about 30 open days, and we must get the clearance for putting it in digital stores (ie submitting) which will take more time, so it might not be available for download in 4 weeks if we really want something smart, smooth and successful. Shrinking the price on purpose to get the job is not my style, my job may seems to be a bit costly but quality has a price and the more the dev is motivated, the better your app will be.
You can drop me a line for further info, I'd be glad to answer so we can start from the good foot, in order to avoid a pretty kettle of fish !