Why are my fish dissapering?

i have a ten gallon 3 black skirts 2 red sarpae tetra 2 black neon tetra 1 big gold fish and one algea eater need hellp fast ive wasted alot of money but evrey day i see some fishes had they ate my 2 zebra dianos idk but i really think is the gold fish or the algea eater please help