I came downstairs one more time to find water on the floor and after further investigation I found that an airline hose had come loose and formed a back-siphon!
I quickly pulled it off the tank and the water level stopped dropping. At least it's not leaking though. I guess I will use plastic plants if they will get eaten. By the oscar wreaking havoc do you mean to the plants or to the fish as well? If the oscar will hurt my angels I will not buy it. I am very proud of my long-finned koi angels and black lace angels and do not want to see them be destroyed. If I do not put the oscar though what other tankmates do you suggest?
However, I also got a real deal. They are in quarantine and cost $4.98 each! 2 Baby Black Ghost Knifefish! I guess that changes the stocking level a little, but they seem to be getting along well so far (no fighting and eating greedily). If they really fight I'll just move one to the 125 gallon, but as for now they are both going in the 180.