My alien creature has ability to manipulate oceans enmasse without any magic ,no technology but only a biological method like powerful magnetic field how could it work? what materials is it reinforcedd to withstand its own field? what compounds are mixed that allows it to create this effect? (All ways like spraying an electric slime stick to control water also)
Energy requirements say No.
My alien creature has ability to manipulate oceans enmasse without any magic ,no technology but only a biological method like powerful magnetic field how could it work?
It's a creature and the inertia of an entire ocean (even a "small" ocean) is enormous. There is no way a biological creature could ever generate this level of power.
To put this in perspective a small tidal wave requires something on the order of magnitude of an earthquake. That's a result of continental plates shifting or a massive shifting of the ocean floor. No single creature could do this.
Water is diamagnetic, which means magnetic fields have very little effect on it (compared with ferro- or para- magnetic materials). However even moving water on this scale using a simple mechanical method is going to require insane amounts of energy.
Very small scale magnetic effects are possible on water but these would be extremely limited for a creature. Think in terms of controlling a very thin layer of water on it's skin, not anything like bulk water masses and not significant parts of an ocean.
There's just no way a biological creature could do what you're asking. The power requirements are many, many, many orders of magnitude beyond what it could conceivably produce.
what materials is it reinforcedd to withstand its own field?
None. Any field powerful enough to do what you describe would fry it's entire system, as all biochemistry is fundamentally based on electron behavior.
what compounds are mixed that allows it to create this effect ? (All ways like spraying an electric slime stick to control water also)
You could control the slime, not the water. You'd maybe get a very small influence on water that stayed in contact (due to surface effects) with the material, but this would not let you make bulk changes to the ocean.
A very small loophole...
A lot of creatures could mechanically synchronize their actions to e.g. generate a wave. It would not be perfect but it would be vaguely plausible.
Really, Really, Really big fins
This is pretty much the only thing I could think of. Magnetic fields do not significantly affect water, definitely not enough for an organism to make waves. The best way this organism could move water is with giant fins.
This is an image of an Killer whale making a wave to knock a seal of an iceberg
So if your organism was something similar, perhaps a whale, or some sort of large fish, it could use it's large fins or even it's entire body to push water, making waves even larger than the ones killer whales make. You probably won't end up with tsunami sized waves, but you could probably make reasonably sized ones, especially if your creatures work in packs.
Thinking of manipulating a lot of water my first thought is the moon and the north sea tides- aka gravity manipulation. Now your creature could maniplulate the orbit of the moon, but it might as well just create extra gravity itself (e.g. by creating a controlled black hole but idk how to realistically give your creature the ability to control a black hole -even if it's self made). But gravity would be the best natural take I can think of.