@boiga:
Edit: Fisher Tiger's dream is "Freedom/Liberation for everyone."
Otohime's dream is "Peaceful reintegration with surface society leading to equal treatment for her people." So, Otohime's dream would eventually fulfill Tiger's dream as well, at least for fishmen and mermen.
However, by his actions Tiger made Otohime's dream impossible in the short term. He hardened the feelings of fishmen against humans and vice versa. This will lead to retaliation on both sides and would have spiraled into open warfare if Jinbe hadn't sacrificed himself and disbanded the Sun pirates.
Fisher Tiger's enemy is the WG, which everyone at FI views as "humans." Otohime's enemy is the enmity between fishmen and humans. If she (or her daughter) can defeat the hatred between the two races, she will succeed in freeing her people. That's the goal here.
If you really think that the violent destruction of the World Government will lead to freedom and equality for all, then Hodi is the real hero of this arc. The battle lines here aren't human vs fishmen or freedom fighters vs the WG, they're hatred vs reconciliation.
And despite his best efforts, Fisher Tiger spread hate.
Well, Tiger used violence to immediately free the slaves that were held at Mariejois, and in order to protect them, formed the Sun Pirates. He said that he wanted freedom and liberation for all, right? However, as it were, many of the slaves that he freed would eventually be shipped right on back the the Celestial Dragons. The Rear Admiral that was following Tiger told him to give back the slaves that he freed. It seems that is one of the primary objectives of the Marines in handling the Tiger business right now. So he had little choice (at least, he thought so) to form a pirate crew and protect them. HOWEVER, I do believe you make a valid point. I think Tiger set out with the Sun Pirates too early. The Fishmen that he has with him think that this is a campaign of retaliation and revenge, and that is the exact OPPOSITE of what Tiger wants. He did, in fact, create more hate and rancor within his pirate crew (and by extension, even all of Fishman island which severely hampered Queen Otohime's efforts) by going out and fighting humans without first making sure the people in the crew knew exactly why they were fighting. The argument between him and Arlong is good proof of this. They had been a crew for a good bit and only then did he disclose what their goal as the Sun pirates were. Again, though, Tiger didn't have much time to do this. He tried to protect the slaves as soon as he released them and pretty much ever since then, has been battling humans directly.