that is a very eire in details on how your Artc died and how mine died, il go threw the details here,
my artc was approximately 4.5 years old and 30-34'' rasied from a very small 4'' baby, he had a very constant diet a mix of shrimp, tilapia , and pellet he was alone for a good portion of his life due to his aggressive behavior towards tank mates this lasted quite some time from about the time i got him to till the artc was a little over 24'' when we finally decided to try him with the other large cats ,rtcs,shovelnose , marble achara, other notable tank mates where alligator gars and a pima, shortly after adding him to a tank with larger tank mates the aggression was gone just like that no rhyme or reason just gone, diet consisted of the same as he was brought up eatting, minus the odd convict that was still in the tank, back in aug of 2018 i woke up to check the tanks every morning like i always do only to find the artc barley hanging on in his favorite spot in the tank he was moved to a 180 gal hoping it would either bring some life back in him or at the very least let him go in peace, 1 hr later he was gone with no reason or cause for his death water conditions were 0amo 1ppm nitrate 0 nitrite 7.3ph , no visible damage on the artc no even so much as a scratch, was eatting well the day before , no change in habits . no outbreaks of any known diseases .it seemly died for no reason that i could find, it was a play back of how my first artc died to the T seemly passing for no reason at all , other tank mates where perfectly healthy and active. ive since got my hands on another one about 6'' long so we will see how it goes this time , they say the 3rd times a charm,