The idea of two large beautiful fish slowly swimming through the air propelled by nothing else but their own tails is just so great! Five stars for that. The implementations deserves less than one star. I still recommend this purchase, but be prepared for the following.
1. Check if the electric motors and the RCs work before you do anything else. The manual recommends to first fill the fish with helium. Don't do that before you check the motors and the RCs. You may need to return your merchandise right away. One of my RCs didn't work right out of the box. It had the red light flashing, so I first thought it was the motor. Then I checked the motor with the other remote and it worked. So, before doing anything else, connect each motor to the corresponding tail fin it is supposed to move, put the batteries in the motor and in the remote and see if they work.
2. If the motors and the RCs work, fill the fish with helium. It has cost me $2.50 for each at a flower section of a neighboring supermarket. You will need to refill the fish with helium about every four to eight days to keep them aswim.
2. When filling the fish with helium for the first time, make sure they pump the gas until all the small wrinkles on the fish skin disappear (the large will remain). This is crucial for gluing the fins and motors to the fish. If you try to glue the fins to a poorly inflated fish, the small wrinkles will be a big problem!
3. Attach a rope to each fish before filling. They have a hole in the middle of the belly for the purpose. Tie the ropes to your wrists or belt. When filled with helium, the fish are much lighter than air. You can easily lose your toy transporting it from the supermarket to your vehicle.
4. Glue the fins and the motor using the included sticky tape. A half of it has stuck to my fingers instead of the fish, so I ran out of the provided sticky tape and had to use my own regular sticky tape. The latter works, but not too well. You will need to reattach it quite often.
5. You will need a helper to attach the fins. If you try to do the assembly alone, you risk letting the fish go. Since they are much lighter than air, they can hit the ceiling quite hard and break the upper fins. Alas, this has happened to me.
6. To make fish swim through the air, you will have to make their buoyancy zero by putting some weights in the compartment in front of the motor. They have some putty in the sets, but initially it's not enough. I had to add a few nails to zero the buoyancy. Eventually, as the helium leaks out, you will have to take the extra weights out as well.
7. Finally, it's time for the positive part. If there are no manufacturing defects and if you have enough time and patience to make things work, then it's just super-cool! We had the fish floating in the garage and it looked like they were real and we just stood at the bottom of the ocean without any diving gear. My 7-year-old was happy, me and my wife were even more happy. It's a great toy, if you can make it working.
8. If things go wrong. The seller didn't hurry to replace my defective RC. After about two weeks of fruitless e-mail communications with them, I filed a claim with Amazon. Amazon customer service is fantastic! They shipped me a new remote. And it works!
9. A follow-up. When the fish are completely deflated, they shrink in size and most of the stuff you worked so hard to glue to them falls off. So either travel to a flower shop every few days to refill, or be prepared for a new round of gluing. Despite all the hardship, we still love the toys. Every kids' party we bring them to is a guaranteed success! However, don't let the little ones touch anything except for the remotes. The rest is way to easy to break.