LunchBox said::OT: so not to sound like a jerk, but do you know tiger muskies get to be 40+ inches long? a 90 is going to be outgrown by 1 of those let alone 4. do what you will, though
back on topic though, adding live plants can help control your nitrites a little in addition to the good water change advice already given
Yeah - I don't go building a house on a foundation of sand dude. The plan is to keep them for a year. They will be 20" to 24" by next June, and then they are being planted into their new home in a 5 acre ranch pond that has a small fish problem. The normal rate for Tigers per lake acre is around 1 to 3 per acre. This is a 5 year project that I am doing (my first time as an aquarium owner, and I know there are some purists out here that are probably pissed off, but that's their problem).