17 running in a 30 tank fishroom, plus a couple 150 gallon tubs. Not going to count empties, my wife might see this.
Time depends on what I'm orienting the fishroom towards. The room is designed for angel breeding, lots of bare bottom tanks with overflows for water changes, no big tricks just a lot of little ones. Maxed out I can pull a spawn every 3 weeks times 5 setups, if I could move that many angels. You're looking at 1-2 hours per night on hatching tanks, call it 15 minutes every other day on 20's for growout, 30 minutes per week on 40b's for growout, 20 minutes per week on pairs. A couple 55's for pairing are 15 minutes, 150 gallon tubs are 30-40 minutes. Bottoms get cleaned, filters get cleaned on the fly, it's a festival of multitasking. Add in an hour for me having a brain cramp and having to mop the floor or some such, some days I suck at the multitasking thing. Toss in feeding & such probably around 16, maybe 20 hours per week, as if I could sell 300-500 angels per week.
I try to keep it to 3 pairs producing or less, some tanks get tied up with side projects, so you could easily half that total. The first couple weeks with angel fry are a black hole of time sucking God like cleanliness, I leave a couple weeks break from this every couple months, and generally take the summer off. Summer might be 2-3 hours per week, I've got a lot of bbq to get done ya know!