Oscar ciclids

Question
QUESTION: I have a 125 gallon tank with a 8" albino oscar, a 5" red oscar, a 3" tiger
oscar, a 5" Pike cichlid, a 5" blood parrot, a 6" green terror, a 5" pacu, a 6"
wolf cichlid, and a 5" jack dempsey. The tank is decorated with slate-rock
put together to form various caves and shelter points. I have had all of these
fish for about a year now and they get along wonderfully. I feed them a
variety of frozen peas, krill, silversides, and once or twice a month I feed
them live goldfish or large roseys. Now, for the first time ever, (i just recently
put in a bunch of artificial plants that extend from the bottom of the tank to
create a canopy over the surface of the water) my fish are creating massive
bubble-nests across the top of my tank inter-twined in the new floating
plant leaves. Who, out of my 9 fish could the culprit be and why would be
they be doing this? Also, no to barrage you with information and questions,
but I've also noticed a very peculiar habit that all of my fish seem to have...
Every single one of them, with the exception of the pike and the jack
dempsey, just float with their mouths just on the top of the water but ONLY
AT NIGHT! Every night, after 9pm or so they embark on this little activity and I
have no idea what they are doing, at first I thought it was because they were
hungry so I fed them, but after eating, they went right back to it. I am hoping
you can shed some light on these questions. I am kind of a enthusiast about
my fish to say the least - they are a fascinating species and I hope to better
understand them. I apologize for the length of this message.

Thank you.

ANSWER: Hi Blake,
 That is really peculiar.  I know of no reason why any cichlid would create a bubble nest, and furthermore, I don't think they could do it even if they wanted to (they don't really have the jaw structure).  There is something else a foot here.   

  The night-time behavior is also extraordinarly peculiar. In my tanks, and in the wild, cichlids inevitably sink to the bottom at night. If it is dark enough, they literally go to sleep during which they either sit or sometimes lie on the bottom, sometimes in little piles -- it is one of the weirdest things I have seen in the wild.  The fact that your fish are at the surface suggests that they are waiting for something to come by?  Is there any possibility that something (insect, rodent, ??? ) might be visiting?  

 (When they are sitting at the surface, are they pumping their gills? That would indicate a lack of oxygen in the water.  I assume that the answer is no, because it would be strange to have such a problem in a large tank, unless you had very heavy plantings in the tank, which is usually impossible with large cichlids given that most cichlids regard plants as the salad course of dinner.)

 By the way, please strongly consider not feeding them with feeder goldfish.  Feeder goldfish are notorious carriere of ick and I have lost too many wonderful cichlids due to infestations transmitted from feeder goldfish.  

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


---------- FOLLOW-UP ----------

QUESTION: Interestingly enough, the "bubble-nests" were gone this morning (I wonder
what it could have been?) - As far as their nocturnal habit is concerned, they
do follow normal sleeping patterns once the light is turned off and as you
described they just sit/lie on the bottom of the tank (usually leaning up
against something). This floating habit I am describing occurs EVERY night
after 9 p.m. and lasts for the duration that my light is on, again with the
exception of my pike cichlid and my jack dempsey, even the pacu (which is
obviously not a cichlid) partakes in this behavior. I am sure it is possible that
small insects (i.e. fruit flies) may be around at times but in very scarce
numbers and certainly not regularly enough for my fish to anticipate their
arrival. The possibility of a nocturnal visitor such as a rodent would be near
zero. The newest member of my tank (the 3" tiger oscar - separated at the
moment by a divider until he can "play" with the boy boys) was added just a
week ago. At first he did not partake in the nocturnal floating but after a few
days, he too began to do the same thing at the same time! I honestly have
not heard anything like this happening before, but sure enough I cannot turn
my curiosity from the fact that it is happening in a habitual manner.

I will heed your advise about the feeder fish - I would certainly like to be
preventative towards anything that may cost me one of my fish. Is there any
other live food that I could feed them? As a ciclid-owner I'm sure you can
appreciate that their eating-habits are one of the most entertaining aspect of
the species.

Answer
Hi Blake,
  It certainly is interesting.  Let me know if you ever figure it out because I have never heard (or seen) such a thing.

  As far as feeding them, you might try crickets.  A lot of oscars and other cichlids love crickets and there are no diseases that the fish can get from crickets.  I don't know how likely roseys are to carry diseases, but having seen how feeder goldfish are imported and distributed I can easily understand why every week (sometimes almost every day) I get an email from someone whose oscar is dying after eating bad goldfish. It really is sad.  

  Try the crickets and see how they like them. By the way, I have an 18" wolf cichlid (Parachromis dovii) and he eats only algae wafers!  You never know with fish.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>