i have kept pike for years, bred them and provided stock for many fishing pools. my two 6" pike are no where near breeding age, my breeding pair of pike are close too 25" in my 5500 gallon pond, i use wave makers to keep the water in my tank moving, and 3 filters, the biggest filter is a 2500lph with a 9w uv steriliser, and a 1000lph and a 900lph so filtration is massive, also got myself a really large air pump as aereation is so important for these fish. you will see how fast these fish grow so you probably dont want feed everyday, i feed every 2-3 days and i only feed minnows because they are a naturally oily fish and the pike digest these very easily! obviously the bigger pike eat more of a varied diet. you will probably need a pond soon to see this fish grow properly, i also find putting oak tree leaves in the tank to give the blackwater effect provides the fish a more natural environment to live in, the temperature in my pond at the minute is 7 degrees, and the tank indoors is 22 degrees (room temperature) i will be building another 800 litre tank soon as i have got fry i need to grow out they are currently 2-3 inch.