Ok so you need to attract the smaller fish to attack the big fat fish. At first this can be a task as got it to attack it once but multiple times was out of the question for me. This was next to impossible when I first tried it. I also read you can eat the smaller octopus and beat the level but I had no luck with that.

iPhone Game Spore

I did however find out how to successfully beat this level 29 of Spore. Here is how.

As stated you need to attract the smaller fish to attack the larger one. You will have to make the smaller fish attack the larger one. The trick is once it is attacking the larger fish swim behind the smaller fish and it will continue to attack just as if you swam in fornt of it.  So get the small fish to attack and swim behind it until it kills the fat fish and EAT!

Good Luck!

So I haven’t found much info on this subject but I beat this level so I wanted to share.

iPhone Game Spore

On level 30 you must steal the eggs from the large jellyfish. You will need to grab a shield. Once you have the shield swim into the back of the jellyfish untill one of the tenticals is sticking to you. Then swim away. The tentacle should now look brown. You will need to pull it off.  I have found I can pull off 2 tenticals each shield. Pull all the tentacles off one by one and the eggs will fall out and float around. EAT THEM. You will be able to find shields in the same place multiple times so you wont run out of shields. Hope this helps!

Good Luck!