A very common deformity that is striking more and more Silver Arowanas kept in captivity today is drop eye, a condition where the eye(s) constantly look down. It is of great debate of what actually causes this conditioned, but a few of the theory can be ruled out or severely questioned, such as a fatty diet. A majority of owners have raised there fish on a low fat diet and consequently
they still acquire it. The genetics theory has flaws of its own, Some hobbyist claim that its the captive bred silvers that acquire the drop eye due to inbreeding causing a weak gene pool, but how can this be when the majority of the countrys silvers are coming out of wild from south America? According to some (consider them semi-unreliable sources) that it is the captive bred silver arowana that are less prone to drop eye, if this is in fact true then is inbreeding really responsible for causing weak genes in fish in general or is it the wild strains of fish that are less hardy than there captive bred counterparts??? .
Getting back on topic, some say that reflection from the bottom of the tank causes the fish to look down.To answer this I did a lil investigation. and this is done on an acrylic tank bottom, not a glass one but I think the result on the glass would be the same. (feel free to question this experiment)
See the reflections??? Thats from our point of view..
Now I took some saran wrap, wrapped up my carema in it, tied it off and made it water proof. The second time, well
..now my camera is drying in front of a fan..lol.. Lets take a look under water from a fishes point of view (I zoomed out as far as I could, the figure at the top of the pic is my aros head)

its the wooden bottom, but Wheres the
reflection????? If theres is no
reflection then what are they looking down at/for??? You might be thinking that the fish would probably be looking down at the tankmates swimming at the bottom level of the tank, but wait
.. what if the arowana has no tankmates???...and theres No
reflection????Then what the heck would the fish looking down for???? Until science (or some hobbiyst with a pay load of cash) steps up, the true cause(s) may remain unknown leaving us to dwell on theorys.