While i have no intention to breed any of my fish, i am curious about this DE phenomenon. There seems to be no conclusive conclusion on it. My last silver had DE on one side. I hope that at least one of my threes will not get any - wins the right to stay inside the house. I hedge my odds by getting three rather than one. I got all three aros from three different fish shops at ~4" (puny juvenilles). Currently all are pushing 16"-18".
The silvers are several month old each.
I got two tanks indoor with silvers. I do not generally use overhead lights (even though i got them).
One tank (72"x18") has two silvers, asian and two marble pims (ex-tank mates were 2 kois and 2 red-bellied Pacus).
The other (80"x22") tank has two arapaimas, silver, jar and bichir.
SO FAR
The silver with paimas shows the most promise. Its eyes are completely like the one of the juvenile i.e. not bulging at all and always looking sideways (i have yet to see it look downwards at all). The plummage is average (no color and not especially deep)
The one of the two silvers starting to show signs of potential DE. The other one is still OK. Both have eyes that are bulging a little bit (yikes). The plumage of both is quite rich (deep) and have slight tinge on edges - very pretty. The lower jaws of two is also protruding more than the single one. Barbells on all three aros are quite nice.
The one living with paimas is leaner than the other two - constant exercise and lookout? It eats quite sparingly (after paimas have had their share). The other two have food abundance due to lack of competition (except among themselves... asian aro waits its turn in general). they are quite chunky.
None of the aros are particularly sociable ...much to my great dissapointment
(i have seen my friends silver beg for food). None of the silvers are jumpers - in any case i do not encourage them to jump. The tank is completely bare except for submersibles so chances of injury during chases are slight. See the example of each.
MY GUESS
The lone silver has to swim alot due to stronger current from the pump. It has to constantly avoid paimas during feeding (paimas are quite violent when eating). It is buddied up with jar which also swims alot due to presence of paimas. Proof of no aggression is a completely presitine fins on jar and silver (no damage to scale either). The only bottom dweller is bichir which hides behind submersible when not in motion on the look out for food. No food is EVER left in this tank. The reflection at the bottom is there because foam is white. The fins are almost totally white =( no hint of color what so ever (much to my dissappointment). The fins are not so deep. The diet includes feeders (from agri farm nursery), crikets, hikari, frogs (very rarely prawns).
The two other silvers have lots of feeders left overs due to their preference of crickets and frogs and pellets (so they definitely do not spend time looking at the bottom for food). Pims usually hide in the corners are motionless except during feeding. Before that there were Kois to look at the bottom. Only one non-dominant aros has not "perfect" finnage. Both have slightly colored fins (love that) . Asian is completely untouched.
PS: excuse the water in paima tank
PS: click on pics for slighly larger view. The first three pics are the aro pair. The last two are of the one living with paimas