Nice promise and very honorable to carry it out.
If it was me then to start with, I would find a tattoo artist that specialises in doing portrates.
The reason I say this is otherwise you may end up with a charactature representation which is not necessarily what you are after.
From what I remember

the fine lines are done with a deeper penetrating needle, so ask about that as they may not be able to do that sort of detail in the location you have specified.
Another consideration is what I think is called bleeding, and I don't mean real blood here, I mean the lines can bleed or become blurry, and I think this happens with a shallow penetration also.
My concern is that the L184 would just look like a black blob, with white dots that may get 'bled into', and you may end up with a black blob!
Also the inks they have today are a lot better than they had a while back.
I have some 'white ink', and it has never needed touching up after 10 years.
If you choose the other side of your foot, ie the top of the arch on the inside of your foot, there is a bit more meat there and it would be a good spot for a profile picture of a fish, and the shape of the foot would give it some depth. A H.zebra would go well there, and with the blue in the dorsal and tail fins it would look cool.
If you are ticklish though the foot may be bad?
I would like to say though that your avatar would come out really well as a flat tattoo.
L134 I think would make a good tattoo too. At the end of the day the fish that you really really want, may just not look that good as a tattoo.
Tats are however very personal, and the meaning is for you, not necessarily what other people see.
Best of luck.