How to add new fish to an established tank

[Tyler9]

This is my very first post so i hope im posting in the right spot. Im hoping to get some advice on how i could successfully add new fish to my current established tank, every time i add a new fish it turns into lunch. So far they have killed a black arowana, a redtail tiger shovelnose hybrid an irridesent shark and a firemouth. All my current fish are under 4".
My current stock list
4" electric blue acara
4" vieja synspilum
3" green terror
2.5" red texas hybrid
2" jack dempsy
2" carpintis
2" firemouth
2" jaguar
1" red shoulder severum
3. 4" red bellied pacu
I know that this stock wont work forever. Just looking for how to curb some aggression towards new tank mates because there doesnt seem to be any issues with the current set up, not much chasing and no noticeable fin nipping or fighting. Thanks in advance for any help yall can offer

 

[BIG-G]

That's some potential big aggressive fish you have listed.
What size tank and any information about your setup would be helpful?
The mix of fish you have is not great. Several of the fish listed will potential reach 12 inches or more and then you have some smaller fish that will not be able to hang with the big guys.
Depending on the tank you may be maxed out!

 

[Tyler9]

Yeah i know this stock won't last long term but i usually pull anything out once it reaches about 8" and either trade it off or it gets its own specimen tank. Tank was sold to me as a 300g but im prettt sure its a 265g 7ft tank. Currently running two 525 gph canister filters and 2 aquaclear 110s. This tank has been set up and running for about 2 years. Only about 2 months with the current stock though

 

[tlindsey]

Welcome aboard.☺ I absolutely agree with BIG-G stated personally would pass on any Aro's and would get rid of the Pacu now because it will be hard to rehome it once it is full grown.

 

[BIG-G]

If you want to know gallons multiply height x width x length in inches and divide by 231.
Even though you have a good size tank I wouldn't add anything. I know you say you trade them when they hit 8 inch or put it in another tank.
How many other tanks do you have ?
The 3 pacu are really the ones that need to be rehoused unless you have somewhere to go with them. And I wouldn't get an arrowana for this tank.

 

[BIG-G]

Welcome aboard.☺ I absolutely agree with BIG-G stated personally would pass on any Aro's and would get rid of the Pacu now because it will be hard to rehome it once it is full grown.

This. you beat me to it!

 

[Tyler9]

Tank is 84x30x24. Arowana idea is gone i cant afford to keep letting these guys kill $200 fish. I actually have a co worker who takes the pacu and he grows them out and eats them. I guess the country where hes from this is a common practice with pacu or somthing. But the jaguar is eventually going in his own 120g (60x26x18) once he starts to show some aggression. My wife picked him out and wanted him in the main tank. It was her birthday and i couldnt say no lol the reason im asking about adding new fish is because she is dead set on getting a blood parrot and i really dont want him to be lunch lile the other guys were. Has anyone had any luck with target/dither fish to help out when adding new tank mates?

 

[BIG-G]

If you are set on adding another fish there are a few things you can do. First feed them well before, they will be less grumpy with a full stomach. Then rearrange the tank. Bust up the territory's they have established. Turn the lights off while you acclimate the new fish get the room as dark as you can. They will settle down a little at bed time. Then add the new guys and hopefully they will get accepted. Leave the lights off for the night then feed again in the morning.

 

[DarylMac]

I think if you removed the South American fish; Pacu, EBA, GT, and Severums, you're left with a stock that could work in that tank.

No guarantees obviously, since those CA fish all have potential to get big, be aggressive, and do some damage.

You could probably add more firemouths (I heard they do better in groups), but realize that when everyone matures even a full grown FM could become lunch for a jag - your aquascape will need to provide lots of hides and areas of refuge where the big guys can't get too.

 

[duanes]

Sometimes with territorial species, it is nearly impossible to add new fish, because at the initial adding of stock, they split the tank up between themselves, and as they see it, there is no extra space.
"Almost" all the fish on your list are territorial, even at a young age.
Some people rearrange the decor to confuse the territorial lines.
Some take out all the fish and add new and old together.
Sometimes these techniques work, sometimes not.
You may be better off waiting until you get a larger tank, and then try new stock with old.