They grow quickly within a year or two to 6 inches and slowly increase in size to reach 12 inches which is the maximum in captivity recorded. A lot of arowanas tend to eat the loaches. Now, if the loaches release their blades found below each eye, then its body will lodge itself in the arowana's throat killing both fish in the process. This is why I will never recommend mixing loaches with arowanas. Both hail from different continents and will never mix well regardless of anyone's claims.

Maybe back to the store?