Is there a swelling on it's barbels and lips? I heard older silver arowanas tend to rub their lips against the glass, causing swelling to the injured part.
i can build you a tank toxic but the freight charges might be over the top
they suffered a bit of damage in the move but have mainly cleared up now
just a couple of barbel to grow back
i started a thread in the DIY section on the filter but can repost here
currently running an eheim 1262? pump and aqua one 2400 canister filter
will change to a large pond master pump when i put another overflow in
another layer of pumice and scoria
needed something on top to spread the water across the pomice as the top layer is "dry"
drilld holes in a piece of coreflute
space on right for pump
plumbed to existing filter, hansen fittings
tap at base to drain detritus
bucket for pre filter, holes to aid spread of flow