New Tank - Platties/ Mollies At Water Surface

[MartinL]

Hi,
I have had my tank running for 2 weeks now, after doing a fishless cycle, and have stocked it reasonably fully – about 150 cm of fish in a 180 litre tank.
I have an external filter, with a spray bar under the surface, but angled upward so the water is very agitated. I have 2 real plants, several artificial, and no air pump or CO2.
Water readings are 0 for Ammonia and Nitrite, water is soft, ph 7.6, Temp 26C

The question I have is this… a few of my fish are spending some of the time hanging at the surface, mouthing. They do this for maybe 5 minutes, and then seem fine. Others in the tank - Tetras, Rainbow fish, Angels do not do this at all and never go to the surface unless feeding. The ones that exhibit this behaviour are platties and mollies, but they only spend some of the time there, the rest of the time they are fine & active swimming in all parts of the tank.
Is this normal, bearing in mind they have only been in the tank for a few days and have done this from day one? Are they looking for food, or gasping for air, or showing normal behaviour?
One of the platties did die after a few days, she seemed to be very sluggish and hang a long time motionless at the top, and in the morning was dead, but the others seem fine and healthy. There are 2 male and 9 female platties, 1 male and 3 female mollies.

Thanks

 

[Gemmylou]

it sounds as though they are ok to me! my guppies did that for a little bit when i introduced them to my tank. they will take a little time to settle down but they should be fine! I hope you prepared for babies as well!!!

 

[OldMan47]

Martin, do you have a recent set of water parameters? Although the actions could be perfectly normal, they also might be showing a bit of stress from a minicycle.

 

[MartinL]

OM47,
As above, Ammonia is 0, Nitrate 0. Have never seen any Ammonia or Nitrite at all after introducing the fish 2 weeks ago.
Just done a water change today, Nitrate was about 40 prior, about 20 afterwards. Is suspect they are just taking time to acclimatise.

 

[waterdrop]

Martin,

I suppose if you are new to the hobby, it could be that you are just observing these fish behaviours very closely. I remember it being quite normal for healthy platies and mollies to exhibit that behaviour. And in contrast angels and tetras almost never went up except at feeding just as you describe, so it could just be that you had a weak individual fish. Platies are relatively tough fish and not so sensitive, so if you had a water chem problem it seems like you'd have symptoms in more of the other too I'd think.

~~waterdrop~~