Threadfin Acara - health issues

[LT Connell]

Looking for information on how hardy Threadfins are from those who own/have owned them. We bought two adults last year (they were a trade in at our LFS) and everything was fine until about 3 weeks ago. One of them looked like he bumped his head, but within a week the flesh was eroding from above his eyes and he died within a week of the first sign of a scratch. The other one started showing possible signs of HITH so I medicated the food with Metroplex and he appeared to be doing better. Eating, swimming, pretty much acting normal.

This morning I fed the tank at about 10:45 and he ate. At 12:25 I walked past the tank and he was belly up. No labored breathing, no signs of "not feeling good".

We have no idea how old they were when we got them, but I have no idea WHY they both died, so I'm nervously watching tank mates for signs of anything out of the ordinary. The one that died this morning was about 6.5" in length, so I'm guessing fully grown. Are these guys super sensitive?

Note: tank is a 300g with tankmates of Blue Acaras, Severum, Clown Loaches, BGK, Tetras, Flying foxes and Rainbow cichlids.

 

[duanes]

Acarichthys need a large tank, with plenty of water changes to stay healthy.
Mine did well for about 3 yearsin a 150 gal with 30-40% water changes every other day, to keep nitrate at a very low level (2-5ppm, they are very sensitive to nitrate toxicity(and I do men nitrate).
I also added Tannins as antibacterial agents, with lots of wood and leaf litter.
I was warned the 150 would be too small, but thought I knew better.
At about 3 years of age, not quite 10" the alpha male started intimidating the others (I had 6 total) to death.
Nothing overt but intimidation no less, the one he chose to intimidate would start to show signs of HLLE, and quickly die, he then moved on to another .
An Acarichthys expert I knew, suggested nothing under 250 gallons, and predicted my outcome.

In the pic below you can see the HLLE start in one.

 

[LT Connell]

Well our tank should've been large enough - 300 gallons! We never saw ANY aggression between the two of them, but within a span of 3 weeks, both of them are dead. So, you're saying they are extremely sensitive to Nitrates? We generally do weekly water changes of at least 25%, but some of them might have crept up to 8-9 days between. We have two Sicce 4.0 pumps running with a wet/dry sump. I gravel vac every water change. They are beautiful fish, but I'm hesitant to get anymore because they seemingly died without cause.

 

[duanes]

The tank should definitely be large enough, in fact perfect size, way better than mine.
There normal water parameters in nature are slightly acid, a pH 6-6.75, although with seasonal changes (dry season/wet season) can sometimes rise to a pH of 8.00. (my tanks average a constant high pH of 7.8, so I had considered them, always at the top end of their pH tolerance) , which may have contributed to chronic infection as adults).
In the book South American Eartheaters, Weidner alludes to adults getting infections in the head area of mature captive individuals.
Natural temps are 82- 86'F.
Since they are omnivores, a pellet containing lots Spirulina was recommended to me.
Maybe 25% weekly water changes were not enough to hold nitrate down, filtration doesn't really control nitrate.