I posted in the other Ebisu topic, but for those thinking Matsya are going to make you really rich, really quick, I'd suggest doing something else. Compared to just NPCing Cave Cherax for full value, gutting those cherax and fishing/NPCing matsya only gets you a little bit more gil/hour, if any.
Here is my haul from when I fished with 125 ex bait.
Assuming 18 Cherax an hour, and getting 21 Matsya, I made 940,000 gil after 30.5 hours (time fishing up 500 cherax, and fishing up matsya, and doesn't include ALL THAT TIME turning in cherax). That's 31k per hour.
I would have made 800,000 if I just turned in all Cherax to a normal NPC for 1600 each. To fish up 500 cherax at 18 an hour, this would have taken 27.7 hours, which comes out to 29k an hour.
Again, this 2k difference is probably even closer to being equal once you consider the amount of time turning in 500 cherax to Zaldon takes. Also, I fished up more than 500 cherax in order to get 125 bait, so luck also factors into your prosperity.
And if my cherax/hour number is off by a little, it shouldn't matter since it's a constant in both calculations. The difference between NPCing all cherax, and spending the time to turn them into Matsya, is still minimal, if there is a difference at all when you consider all time factors (crappy fishing days, Zaldon gutting CS, etc.).
In sum, unless you want bragging rights for the largest fish on your server, don't bother with Matsya at the moment. There are plenty other, significantly more profitable fish.
E: Theoretically, of course, you might be able to up your profits if you get a bunch of people to hold fished up mobs in Vunkerl. Since mobs account for the most loss of bait while fishing Matsya, if you can have people hold them while you fish, you'd be saving yourself a lot of bait. But be aware that the mobs do gain in strength over time, so your partners would need to zone them every once in a while to reset their strength.
That's a lot of work, though, and I don't think it to be worthwhile.