Arowana bleeding through gills?

[5thColumn]

Hey everyone, so a couple weeks ago my friend put his 7'' silver arowana in my tank. I have a 12'' silver arowana along with other tankmates. I found his arowana floating face up the next day, barely alive, with blood flowing out of his gills. I could not find anything online about what had happened, and he died shortly after. I examined him completely, no scars or any marks from fellow tankmates. Any ideas as to what could have happened?

 

[ringoyam]

no idea

 

[chloe]

nope, but hope someone on here does.x

 

[xander]

what are your water parameters and what were the params on your friend's tank?

 

[BigO6687]

what are your water parameters and what were the params on your friend's tank?

+1
and what are those other tankmates

 

[Bderick67]

Many times aros will kill other aros just by simply chasing them to death.

 

[5thColumn]

I'll have to get back to you on the water parameters, haven't checked yet. Don't shoot me, but the other tankmates are two spotted gars, a jardini, and a tiger shovelnose. And trust me when I say, there was ABSOLUTELY NO damage to the arowana. I figured that would've been the first cause, but he didn't have a single scratch, just massive internal bleeding from the gills.