Cardinal Tetra

[Supraman]

So recently I discovered I have a liking to these colorful little guys, also love how they shoal together. Tomorrow I will be purchasing a 20 gal tank and will be stocking some tetra once cycled. My question is, how many can I stock in a 20 gal long tank. I know that the 1 gal of water per 1" of full grown fish rule is kinda outdated but would it still apply to small fish such as the cardinal?
 
I plan on a sand substrate, planted tank with LED lighting. thanks in advance.

 

[Ninjouzata]

I meant to ask..do you want just them or other fish too?

 

[Ryan10]

I would start with 10.  That way if you want to add other species like amano shrimp or ottos you'll have room for expansion.  The tank idea sounds great.  I really like how cardinals look in a planted tank.

 

[Supraman]

I'd just like the cardinal. It's like a small start towards my end goal with the 237. This way I will have a decent number of cardinals before hand. Cause in a 237 I could more then likely have 100+

 

[AquaPit]

if its just Cardinals.. 8-10 looks nice..

but if you want to see them shoal tighter, you have to trigger a sense of defence mechanism in them..

for eg.. my neons usually get tight when they sense my GBR is nearing them.. you know what I mean..?

Although you guys know GBR is quite peaceful..

Correct me if I am wrong..

 

[eaglesaquarium]

The inch per gallon "rule" is only for small fish like cardinals. Imagine a ten inch oscar is a ten gallon tank.


Also, 100+ would be far too many in the 237 gallon tank. Think more along the lines of 50, especially if you plan to add discus as well. Discus require very low nitrates. Heavily stocking just isn't possible with them.

 

[Supraman]

Ah yea I suppose I didn't take the discus into account with that number.

So what would be the most I could have ? 10-15?

 

[eaglesaquarium]

No, you could easily do 25-40 cardinals, even with the discus. 

 

[Supraman]

oh no I was meaning for the 20 gal but now its a 40 gal long.

 

[eaglesaquarium]

40 G long?  20 cardinals, once its fully cycled.

 

[Supraman]

already done haha, I seeded it and tested it with 4ppm of ammonia. It was gone in less then 12 hours 2x so it wasnt a fluke.