Angels Nears Heater

[ducas005]

Hi all. I have a freshwater 45 gallon tank with a betta, 5 mollies, 2 Irid. sharks, 2 platies and 3 angel fish. Lately whenever I switch on the light the angels go near the heater, at the top of the water and stay there. The heater is submerged till the level indicated, and i mantain water temp around 26 degrees celcius (78.8 F). Tank is a year old, contains a few live plants, and lots of plastic plants.

 

[Allivymar]

What's your water parameters? Ammonia, nitrite, nitrates? They may be looking for oxygen (levels are higher towards the top of the tank). Do you usually feed them at that side of the tank? Maybe they think they're going to be fed. Are they acting unusual in any other ways?

 

[ducas005]

Hi. The tank is a year old was well cycled before stocking started. I haven't tested the water, but no new fish have been added for a month (the last one was a female platy), and I havent seen any outbreak of any diseases. As you can see, right now I only have 13 fish in the 45 gallon, of which only one of the angels are large. I also have 6-7 plants (amazon, giant hygro, anubias).

This morning when I was feeding the fish before work, I couldn't find the large angel anywhere (the other two are small). I didn't even see him yesterday Usually he is the first one to go up to the water surface during feeding time. The other two angels were behaving normally again (not going near the heater and staying there).

1. Should I quarintine the two angels?
2. Do fish ever disappear? Sounds impossible.