Sick arowana?

[NickGalante]

i have a black arowana about 5 inches, we bought him around November 2021, its now 2/21/22 and he has not grown an inch . we just recently started feeding him tilapia instead of blood worms and flakes. he was originally in a 125 gallon fish tank, but we noticed him darting around a lot and jumping . so we moved him to our 300 gallon tank , 8ftx3ft. he wont swim anymore and stays in the corner barely moving, these are the water parameters ph: 6.5 ammonia : none nitrate 0ppm , nitrite 0 ppm , can anyone tell me why my arowana isn't active anymore in the 300? or why he wont grow at all?

[Autumnsky]

Have you seen his poop?

Are you familiar with what it would look like if he has internal parasites?

Can you look at his body, gills, eyes mouth, anal vent for any worms or tiny specs white, gray or black, could be fish lice.

As for feeding, a variety of foods would be better than a single food type, could be some deficiency.

My first guess would be internal parasite. The flashing would possibly indicate a Nitrate spike in the water before, or external parasite.

Were they live blood worms? Often live worms cultures can carry unwanted organisms.

This might help with some direction for illness.
https://www.aquariumadvice.com/fish-...and-treatment/

Do you have other fish in the tank which could be intimidating this little guy?

edit - adding too that some hiding places would be nice.

[NickGalante]

we havent seem him poop, or havent payed enough attention to see him poop , gills are normal , everything on him is normal , as for his tank mates nothing goes near him , we also found out if we turn the aquarium lights off he starts to swim a bit, for food, the blood worms were frozen , then un frozen and given to him , we stopped feeding him tilapia and blood worms and are now feeding him hikari jumbo pellets which he eats in a few days

[Autumnsky]

What are the other tank mates and sizes in comparison to the fish.

It sounds like it could be stress and or internal parasites, but for me very hard identify something with out an obvious sign, to fix a problem like this when it seems every thing is "normal".

Something is not normal when the fish is not behaving in a usual manner.

I would add some floating fake or real stem plants to add some shade and maybe the tall, same around the area it seems to want to hang out add more hiding areas. Even if it is a temporary measure to get the fish more comfortable in the tank.

You could also add a piece of screen at the top on the glass top and under the light to create a subdued area during lights on time.

[NickGalante]

the tank mates are a 5" pleco , a bichir , 8" and 3 clown loaches around 3" thats it. the arowana has been in the new tank only of days i will add some hiding places and floating plants., would you like pictures of the arowana?