Originally Posted by Dut
Only thing that jumps out at me is that the tank is overstocked. Most of the members here will tell you that a 50 isnt large enough for one Hippo, more less two. Mandarins ussually need about 100 lbs of LR to find enough pods to survive(im not sure how much LR you have) so with having two of those as well I would think they would clean pods quick in a 50. All of that then add a larger angel and a couple clowns and its alot of bioload in the tank to handle.I would think the ammonia had to come from the bioload, overfeedinig, or somthing that happened during the move that has been undetected for the last couple of months. Maybe there has been small ammonia spikes since then that youve been lucky enough to survive, some of the bacteria could have been killed off during the move which might have contributed to the tank not being able to handle the bioload anymore.
Did you test the water after your move? Are you sure that no small ammonia spike came from that? Someone will see this and be able to help much more then myself, more details would be good.
What is all of your parameters? (ph,ammonia,nitrite,nitrate,etc) Id tests everything you can test for.
How much LR?
The part about Mandarins isn’t 100% True. I have a mandarin in my 25 gallon tank and he has become well grown and very FAT... He has been in my tank for 7 months and when I got him he was skinny and underfed. He eats all day off of the 25lbs of live rock I have in my tank, so 100lbs isn’t always needed. Just a good population of pods and well established rock, so it really depends on the situation of the tank.
I will agree that “2" Mandarins is a bad idea and with ammonia present in the tank, the pods could have been killed off with other creatures and bacteria in the move so the Mandarins could have been starving over the last 4 months.
Also, any amount of ammonia could have killed at least one fish and that could have spiked the levels enough to kill all of the other fish. If I had to guess, the Mandarins were most likely the first to die, if they were starving.
As far as the green in water, is you tank getting a lot of sunlight? Near a window? I had a problem with algae in my water, making it appear green that was caused by direct sunlight during the day.