Oscar Tank Needs Help!!!

[Mavrick813]

Set-Up:
265 Gallon Aquarium
FX5: Media Seachem Matrix
FX5 2 : Media Seachem Denitrate in 2 Baskets and Matrix in 1 Basket
Eheim Classic 600: Media Seachem Denitrate and filter Pads, Topped with Filter Floss
TurboTwist 36W: On 24/7
Ligting on 6 hours daily.

Water Params, 81* F
Water test 0, 0, 15

65% Water changes weekly, conditioned with Seachem Prime, and Stress Coat.

Original Stock,
1x 9" Rhino Pleco
1x 6" Sailfin Pleco
2x 3: Bushynose Pleco
2x 3.5" Pangasius Catfish
1x 3" Featherfin Ctafish
20x Giant Danio
13x 2-3" Oscars
2x Electric Blue Acara
1x Male Blue Convict Mated in Aquarium
1x Female Pink Convict Mated in Aquarium
20-30 .3" Baby Convicts.

Aquarium was started on 11/1/15. Fish stock was built over the course of 2 months. Convicts Bred on 12/4/15

Issue: Last week I lost an Oscar. He looked almost white/scaleless on the bottom of the tank in the AM. I suspected foul play from a pleco and brushed it off after testing water and getting 0-0-20

2 days later I found another dead Oscar. similar conditions, Water still 0--0-20. I did a 65% water change upped the temp to 82* and Dosed with Rid Ich as I seen a couple of small white spots on the Acaras.

The next day I discovered another dead oscar. Frayed Fins, White flesh, hazed over eyes. I performed another 50% water change and dosed the aquarium with Salt.

The Next day I discovered 2 more dead oscars and 1 not looking so well. After talking to LFS and showing them the dead Oscars they recomended a Heavy Water change and a series of Quick Cure. 3 Doses over 24 hours. Followed by another heavy water change.

Today I have 2 moire dead Oscars. Water Params are 0-0-5 ish temp is 82*, I have 7 oscars left all of which are eating, 1 has a small wound near his jaw which i figure is from him digging gravel. I have not lost any other Fish beside Oscars. I am completely lost as to what may be causing this.

Lastly: I know the aquarium is severely overstocked. The long term goal was to pick a few oscars of the bunch that looked the best and keep them and passing the rest off at the LFS. This is not my first aquarium and figured with Adequate heavy water changes the aquarium conditions would be fine until the oscars reached about 5-6" at which point I would begin weeding out the ones that i didn't care for.

Please advise as Id hate to lose any more of my fish...

Mike

 

[jsodwi]

Only losing oscars? is there an alpha that could be bullying? I could see that with a few but you had a bunch together. It doesn't seem overstocked yet. 265g plenty of filtration and the fish are babies

 

[Mavrick813]

Agreed, I thought a bully was the culprit as well. But it doesn't seem so at this point.

I was thinking maybe a bacteria or parasite that's affecting organs. The one Oscar showed Swim Bladder symptoms with rolling and flipping randomly.

I Was contemplating a round of Furan2 or Maracyn 2.

Please advise

 

[Rocksor]

Maybe it is the convict pair taking the oscars out one by one due to them having fry in the tank. Any chance you can remove the pair to another tank?

 

[justarn]

They aren't choking on baby cons are they? Maybe they have been eating them and they are now just to big, check their throats if any more die...
Watch for symptoms on the others and post any results, are their faeces OK? Not bloated at all?
Weird it's only affecting the Oscar's, it could be bad genes I guess if they are produced via multiple in breeding but then you wouldn't expect them all to be dropping so close together...

 

[justarn]

Your Oscars should be 10 inch long if they have been in there a year, is that what your saying? You stocked last Feb March?

 

[Mavrick813]

Your Oscars should be 10 inch long if they have been in there a year, is that what your saying? You stocked last Feb March?

No, I stocked nov-dec.

I checked throats for con babies and found none. No swelling or deformations at all.

Mike

 

[pops]

how long has tank been established, not want to say tank is over stocked but will say crazy stalked. they may be small, am I reading right, 20 to 30 convicts, 13 oscars? let alone the rest? that is crazy talk my friend. if i am reading right the die off has just begun.

 

[Mavrick813]

how long has tank been established, not want to say tank is over stocked but will say crazy stalked. they may be small, am I reading right, 20 to 30 convicts, 13 oscars? let alone the rest? that is crazy talk my friend. if i am reading right the die off has just begun.

You are reading right Pops, I had kept a breeding pair of cons and 5 Os in a 180 for 8+ years until I had a stand / tank failure and lost them all.

The idea was to grow the Os out until they were about 5-6" and keep the best of the best at that point and donate the rest to the LfS,

 

[Mavrick813]

The two fx5s were established for several years on my 40g breeder, they were moved over to the 265G on 11/1/15 when I got it. The Eheim Classic and Turbo Twist 36w were added later that week.

Fish stock to begin with was, Rhino Pleco, Sailfin Pleco, Bushynose Pleco.

Fish were added a few at a time over the next 2 months.

All parameters have read 0-0-20 for the most part with weekly water changes of 50%+.

All water changes include a dosing of Seachen Prime and Stress Coat for the replaced water...