For my son's third birthday party my husband and I (along with my son) decided to have a "Fish party." I  found Under the Sea invitations at a local party store  and also bought matching plates and napkins. We decorated the house with dark blue, light blue, aqua blue, and green streamers and balloons. We did not spend much money or time on decorations because  we decided to focus on the games and activities for the party-goers. We had three different things for the  children to do at the party, and we found that they  loved all three of them and were busy the whole time.  For the first activity, we made about three dozen fish   (2 different styles) and starfish out of colored foam  "paper," drew gills and stripes on them with Sharpie markers, and glued google eyes on them. Then we  put large paper clips on their mouths for lips. My husband made four fishing poles out of dowel rods  with string "lines." He strung the poles by screwing metal "eyes" down the length of the pole, threading  the string through it, and then winding and taping the  extra string along the base of the pole to make it look  like a "real" fishing pole.  At the end of the strings we  tied on paper clips and then superglued small round  magnets.  We put the foam fish in two blue  Rubbermaid storage totes and decorated the outside  of the totes with green construction paper seaweed and construction paper fish, crabs, seahorses, starfish, and octopi.  The children at the party loved playing with our homemade magnetic fishing game  (and my son played with it for about 2 months after the party).  Hint: You can glue almost anything onto a Rubbermaid tote with a gluestick and it will just peel off later when you want to remove it.  We also had the children decorate fish hats. My mother got a few  dozen Krispy Kreme donut hats (those rectangular  paper hats) and brought them to the party. We cut out about 4 dozen rectangular-shaped fish (kind of like  trout) and had markers, glitter glue, and google eyes for the children and adults to decorate fish. Then, we  glued them onto the Krispy Kreme hats and everyone at the party walked around with fish on their heads. The children thought it was extremely funny. We also  had live goldfish races at the party. My husband made  two racing troughs out of a piece of PVC pipe that  was approximately 5 feet long and had a diameter of 6 inches. He used a table saw to cut it down the middle and then made braces, or feet, for the troughs  to rest on. He used a special sealant/glue to secure  plastic caps to the ends, and away we went! The  morning of the party my son went to the store with my husband and bought 20 feeder goldfish. We put them  in a large goldfish bowl that had green and blue  rocks in it and placed it on the table in our entryway for everyone to see when they came into the party.   About 1/2way through the party we spread a green and a blue plastic tablecloth on our hardwood dining room floor, brought in the troughs, filled them up with  water, and had goldfish races. It was so much fun!  After the goldfish races we had cake and ice cream. I made a large sheet cake (bigger than 9x13) and frosted it with blue frosting then crushed up graham crackers to make a beach and made green frosting to make seaweed. We then put plastic sea animals  (octopi, whales, dolphins, fish) on it and made them  look like they were swimming or "beached." For  drinks I took a large clear glass punch bowl and made blue koolaid. I floated an ice ring in it that had  gummy fish and octopi frozen in it and also made ice cubes each with a little gummi fish in it. The children  thought it was funny to be drinking "sea water" with surprises in it. Finally, as the children were leaving  the party we had them "fish" for their prizes. We took  a large cardboard box from a t.v. set my parents had bought (I think the dimensions were about 4' high x 6' wide after we cut it down some). We covered it with a  thin blue plastic tablecloth and glued construction  paper seaweed on it and lots of construction paper fish and sea creatures on it, including two sharks and some dolphins (extra paper animals and fish that we  made were taped up on the doors and walls of our  house, with a giant paper shark taped on the front door for the guests to see when they came to the  party). Toward the end of the party, my husband snuck away and hid behind the panel with the goodie bags at the ready. As the children were leaving they  used the fishing poles from the magnetic game to  "fish" for their goodie bags. We had taken clear plastic gift bags and loaded them with goodies (a  plastic sea animal, shark fruit snacks, sea animal stickers, a fish pencil, and goldfish crackers for the older children--- a plastic bathtub book, a plastic  squirting fish and goldfish crackers for the babies), tied them with strings, and attached paper fish to  each one with the child's name on it. When the  children went to cast their poles over the panel, I  would tell my husband who was there fishing, he would find their goodie bag, hook it with a loop in the  string holding it shut onto the paper clip on the fishing  pole, and shake it around before they "reeled in" their catch. It was a great way to pass out the goodie bags,  and some of the children couldn't figure out how their  bags were getting onto their poles!  Some of the children also got to take home a few of the live  goldfish. We made sure to warn the parents in advance and ask their approval before just dumping a live animal on them. A few of the families declined to take fish home, which was fine because we wanted to keep some for ourselves anyway, but quite  a few of the children got to home with real fish. All in all, the party was great fun and was relatively cheap.  The supplies for the poles and troughs were inexpensive, the construction paper for the fish was something I already had at home, and the feeder  goldfish for the races were, almost literally, a dime a dozen!