I guess the attack only partly hit the fish thus shooting it further sidewards.

Training brings you growth in experience, mental and physical power. Rokushiki depends only on physical abilities not willpower but that doesn't make the training otherwise useless.
The WG isn't the only one teaching Rokushiki, the marines do as well.
I still don't see an argument why Tekkai can't be a pre-step to Busoshoku Haki. If mastering it takes longer than the other forms it only reinforces this theory. Other forms remind us of the typical combat forms as well, e.g., how Kami-e is similar to the application of Kenbunshoku Haki.

I also don't see how Rokushiki makes it hard to use Haki? As I said before both are independent of one another and what does it matter who uses this ability?
Having chosen agents without Haki doesn't make the WG unaware of this power and likely CP-0 posses it. That strange reasoning is has nothing to do with our topic.
@Greg:

Sure is. It's why I was careful to choose my wording.

'Willing' to learn.

I didn't just mean someone who 'wants' to, someone who actually has the willpower and capacity to learn it. It's not like I'm suggesting Corgi is going to bust out double-fist busoushoku.

Here you're just playing with words. If someone is capable to learn it they'll be able to. That's a tautology. So in the end it's still a fact not everyone is able to use Haki even if they tried to.
That would explain why a 28 old Lucci didn't use any haki and was defeated by a talented 17 old.

@Greg:

Some may. But we've seen an awful lot that don't. Plus, there's simply no comparing the length of training we've seen to what CP9 was subjected to training from childhood as clearly seen in Chapter 0.

Whom?
Luffy has been training since his childhood, Rebecca has, Ace has, etc.
Coby applied only Soru as in both instance he planned to punch Luffy but was too slow. Still, it's possible he was learning general Rokushiki basics.

@Devil:

No, hell no. It's got nothing to do.

First, quote the whole sentence or semantically correct part. "though" is an important word that classified the following as a side note.
Second, you don't know how Pekoms bounty can be interpreted. Although we know he uses Haki and a DF he's bounty is as low as Kid's pre-timeskip. So what I said is not wrong, if you look only at his bounty he doesn't appear to be that strong.
@apologized:

does rebecca avoid fighting fish or that's just sabo

not clear for me

The fish is too fast for her.

@apologized:

sabo with King Haki ?

Imho he doesn't seem to be the type. But possible since he's Luffy's and Ace's brother.

@Light:

Guess we are interpreting hero differently here. As far as I'm concerned, a hero is someone with heroic motivations, such as greater good.

I didn't read the whole conversation but that bit bugged me. Doing something for "greater good" is not a heroic motivation and it doesn't describe fighting for other people.
It is a choice, often a difficult one and by no means always justified by the right motivations if it is possible to distinct what is a right one at all.

@Nycprodigy:

Robin is an assassin really. It's probably a good thing that she's more of an observer than a talker.

I know her power is hax especially in this situation and she's smart, probably too smart in her situation. But those aren't qualified reasons to diminish a character over many arcs.

Btw, I don't it's necessary to quote the whole post just for one of the last sentences.

@Greg:

That's obvious. I don't think anywhere in my post did I suggest anything that contradicts that.

Your very own post points out the futility of bothering to learn Tekkai.

Everyone has haki but not every can learn to use it and considering that all known Busoshoku Haki users were strong it is likely a certain level of power has to be achieved. Rokushiki seems to be a way to do it by training.

Armaments doesn't take years of arduous training for those willing to learn.

That is not true. Rayleigh said that people can fail to learn haki despite training.

Moreover, you need arduous training for Haki, too, and it takes years to master it. Coby and Helmeppo learned Roukishi basics pre-timeskip so they didn't even have years for their physical training.

A kyah?? She's really portrayed being weak. Now if she wins the haters will really snap.

@Greg:

Oda (probably) did not plan the specifics of Haki at all from the start but he knew damn well that it existed and that he was going to use it as the series' 'Lifestream'.

Regardless, there's so very much about Haki that feels tacked as even as recently as CP9, all thanks to Color of Derpaments.

Tekkai is something far easier to break than Armaments, but in most cases requires one to be stationary to use? And it takes how long to master??? Tekkai ftl.

Armaments is without a doubt, one of the weakest elements in the story and probably an escape route more than anything else.

King's Ambition and Kenbunshoku were probably in basic forms, if not a single concept, from the start and Armaments simply turned out for the worst.

It remains cool in execution but wince-inducing on each read through.

Everyone has the power but not everyone is capable to use Haki even after long training and it is independent from Rokushiki as it depends on willpower while the latter on physical strength. So it is probably taught by the marines just like a martial art by the marines and the WG, and those who talented can learn Haki afterwards. BB indirectly told us that a person can unconsciously use Haki in combat so anyone who can go beyond Tekkai would be taught how to use Haki.

I agree Oda didn't provide a sophisticated explanation of both powers thus leaving a lot of unresolved issues that can't be deduced or interpreted by the reader, however, that is true to many topics in the manga.

@Lifeswork:

One thing that I was thinking about the container, is what if all the fighting fish had one. I could easily see DoFlo not having the Mera Mera in the Colosseum right now, and only putting the mera mera in if there was going to be a clear winner that could catch all the fish. All you need is a one way tube under the water that you can put the fish through, and you have a near unlimited supply of fighting fish, so if the fight is really close and everyone drops before "finding" the mera (because it isn't there), he has the plausible denial.

Considering no one counts all the fish with Haki and remembers their number plates thus noticing any new fish.