What is the biggest fish I could keep in a 200L tank?

[Conchonius]

i thought that since they get 40cm and the tank is 122cm they would have 3x their lenghth which is long enough but do you need more?

You would need more. A lot more.

Since we're land animals, and our "model" for a pet is a dog, we tend to think that all a fish needs is the equivalent of a kennel for it to live in. That is not so. Fish can't leave the water they're in, so they need that kennel, a yard to run around in, and a sewer system to process their waste. As a consequence, even small fish need a lot of space compared to their body size. For active fish such as cichlids or your silver perch, something to the tune of "tank length must be 10x fish body length" is not an unreasonable rule. You can keep them in smaller tanks, but they won't grow to full potential and be more stressed/less "happy" in general.

You can somewhat avoid this by keeping more sedentary fish, who are less like dogs and more like snakes in temperament, and will be fine as long as they're kept clean and fed. But even they will need some heavy filtration to maintain the "clean" side of the equation. And yeah, you'll have problems if the fish can't even turn around in the tank when at maximum size.

 

[Mod123]

You would need more. A lot more.

Since we're land animals, and our "model" for a pet is a dog, we tend to think that all a fish needs is the equivalent of a kennel for it to live in. That is not so. Fish can't leave the water they're in, so they need the equivalent of a kennel, a yard to run around in, and a sewer system to process their waste. As a consequence, even small fish need a lot of space compared to their body size. For active fish such as cichlids or your silver perch, something to the tune of "tank length must be 10x fish body length" is not an unreasonable rule. You can keep them in smaller tanks, but they won't grow to full potential and be more stressed/less "happy" in general.

You can somewhat avoid this by keeping more sedentary fish, who are less like dogs and more like snakes in temperament, and will be fine as long as they're kept clean and fed. But even they will need some heavy filtration to maintain the "clean" side of the equation. And yeah, you'll have problems if the fish can't even turn around in the tank when at maximum size.

So that rules out all perch species, catfish, bass, cod, grunters. So theres not many fish of that sort of size/shape besides cichlids right?

 

[Hybridfish7]

Oh ok. So should i just assume the pet shop things are wrong for the fish? thats where i am getting my info lol

For the most part they tend to be... with things like amatitlania sajica a lot of "pet info" sites say 10-15 cm is the max size when in reality they can get about 25

So that rules out all perch species, catfish, bass, cod, grunters. So theres not many fish of that sort of size/shape besides cichlids right?

gudgeons
what do you think of these guys?
species from the Mogurnda genus, aus native and fits the size bill

 

[Mod123]

For the most part they tend to be... with things like amatitlania sajica a lot of "pet info" sites say 10-15 cm is the max size when in reality they can get about 25

gudgeons
what do you think of these guys?
species from the Mogurnda genus, aus native and fits the size bill
View attachment 1546917View attachment 1546918

These do look nice, are there any peacful fish that look like peacock bass that fit the bill? Peacock bass are some of my favourite looking fish

 

[Conchonius]

So that rules out all perch species, catfish, bass, cod, grunters. So theres not many fish of that sort of size/shape besides cichlids right?

Not really. Full-sized perch and grunters are out, but you can do pygmy perch even in numbers. There are dozens of suitable catfish, the issue is that most of them are South American, you're in Australia, and they've got very strict animal import laws over there (and for good reason). If striped raphaels go for 250 AUD, I dread to think what cactus plecos are sold for.

You do have the advantage of some really unique native fish. I'd keep something like mouth almighty or that one endangered gudgeon you've got there, if I were in your place.

These do look nice, are there any peacful fish that look like peacock bass that fit the bill? Peacock bass are some of my favourite looking fish

Altolamprologus compressiceps is as close as it gets, and will fit a 120 x 45 cm tank. Not what I'd call peaceful, but maybe a pair would do.

 

[Ogertron3000]

Where abouts in Australia are you?
Some of us aussie members can recomend some good shops, also Friller2009 is bit of an expert on aussie natives if he sees this he will have some suggestions and sources you want natives

There are much better shops than coburg aquarium, they have a great range but the staff are pretty dodgy, much better options in that part of the city if you are in Melbourne.

 

[Mod123]

I

Where abouts in Australia are you?
Some of us aussie members can recomend some good shops, also Friller2009 is bit of an expert on aussie natives if he sees this he will have some suggestions and sources you want natives

There are much better shops than coburg aquarium, they have a great range but the staff are pretty dodgy, much better options in that part of the city if you are in Melbourne.

I live in the southeastern suburbs

 

[Mod123]

Not really. Full-sized perch and grunters are out, but you can do pygmy perch even in numbers. There are dozens of suitable catfish, the issue is that most of them are South American, you're in Australia, and they've got very strict animal import laws over there (and for good reason). If striped raphaels go for 250 AUD, I dread to think what cactus plecos are sold for.

You do have the advantage of some really unique native fish. I'd keep something like mouth almighty or that one endangered gudgeon you've got there, if I were in your place.


Altolamprologus compressiceps is as close as it gets, and will fit a 120 x 45 cm tank. Not what I'd call peaceful, but maybe a pair would do.

A cactus pleco is 375

 

[Ogertron3000]

I

I live in the southeastern suburbs

cool, my old neighbourhood, I grew up in endeavour hills.

check out New Life Aquarium on Cheltenham rd in Keysborough. It looks like crap from the outside buy is very different once you go through the door. There are2 othershops nearby but they are the best by far.
Also lots of fine in narre warren is worth a visit, the owner is a bit strange but knows his stuff. He might try to get you to join his church .If you feel like a drive there are a couple of decent shops in Frankston too.

 

[Mod123]

cool, my old neighbourhood, I grew up in endeavour hills.

check out New Life Aquarium on Cheltenham rd in Keysborough. It looks like crap from the outside buy is very different once you go through the door. There are2 othershops nearby but they are the best by far.
Also lots of fine in narre warren is worth a visit, the owner is a bit strange but knows his stuff. He might try to get you to join his church .If you feel like a drive there are a couple of decent shops in Frankston too.

thanks i'll check them out