20 Gallon Tank Should I shrink my Lemon Tetra school ?

Let me start off by saying I'm pretty new to this hobby.

I've got 9 Lemon Tetras in a 20g tank, and I only just found out that there's 2 males to 7 females.

Although my tank is almost long (24"), with 9 tetras it seems possibly too small for them. I'm wondering if I should get rid of maybe 2 females? I've read Lemons are generally very friendly and laid back... Not mine!! From day one they've been very rambunctious and intense, always chasing each other and eating voarciously.

I'm worried now the smaller tank is effecting them because they've gotten aggressive. I came home to my snail half out of the water and the Lemons leading the whole tank in an attack against it, they were swarming it and had ripped some flesh off. I think he will be okay, I separated him. But something needs to change.

Also in the tank is 7 Galaxy raspboro, 2 honey gourami, and 1 pleco that is 4 inches. It's fairly heavily planted although I'm adding more as quickly as they nibble the plants apart so it's a losing battle. I've tried to make spaces with decorations, it's a WIP. There's also wood for the pleco.

My gut tells me I should rehome some but I don't want to stress out my lemons by making their school too small by mistake. Any advice is appreciated!

 

I have read some who say that larger schools reduce aggression. I do not know personally.

I have 20 Harlequin Rasboras in a 20 long. They behave similar to the way you describe your lemons. I like their activity and voracious eating. They are the only occupants of that tank now.

I like large schools of small fish. I do not know how big lemon tetras are.

Sorry not much help.

 

Welcome to fishlore!

I wouldn't decrease the school size. Having larger schools decreases aggression and stress.
I think the tank is a little over stocked imo. Personally I would remove all of the lemon tetras since they need larger tanks.
Be aware that most types of pleco get too large for a 20 gallon.

 

Welcome to fishlore!

I wouldn't decrease the school size. Having larger schools decreases aggression and stress.
I think the tank is a little over stocked imo. Personally I would remove all of the lemon tetras since they need larger tanks.
Be aware that most types of pleco get too large for a 20 gallon.

Thanks for the response!
I'm actually not sure if what I have is a pleco, I got it from my friends goldfish tank when he died so there's a chance that it's growth was majorly stunted. Not sure if it will recover from that..? I will re-home him though if you think that is the case.
What size tank would you recommend for the Lemons? I read 10g is the minimum size, but after seeing how my relatively small school behaves in 20 (and this was even when they were the only inhabitants in the tank), I feel like they'd need at least 30g looooong
In any case, I do plan on upgrading my tank, but unfortunately that's not an option until I'm able to move (which is difficult with covid). Do you know any way I could make the tank more comfortable for them/their tankmates temporarily? (Like ideally upgrading next month but realistically could be a couple months).

[In terms of tank health, I notice a lot of poo lol so I gravel vacuum and 20-30% water change every couple days, plus I have a 30g rated HOB filter, so hopefully that helps mitigate some of the environmental issues arising from the many inhabitants]
[Also more plants are going in today]

 

Let them settle. These fish aren't agressive but simply adapting / settling hierarchy. The pleco is the issue here. This one will be the same size as the tank ! Swap that one

 

Welcome to Fishlore!

The spotted one on the left will need to be rehomed, as DoubleDutch mentioned. That is a common pleco, and those can get REALLY big. Once they are fully grown, they will need a tank in the hundreds of gallons. The only reason they are kept in smaller aquariums is because pet stores sell them when they are really young.

 

Welcome to Fishlore!

The spotted one on the left will need to be rehomed, as DoubleDutch mentioned. That is a common pleco, and those can get REALLY big. Once they are fully grown, they will need a tank in the hundreds of gallons. The only reason they are kept in smaller aquariums is because pet stores sell them when they are really young.

Let them settle. These fish aren't agressive but simply adapting / settling hierarchy. The pleco is the issue here. This one will be the same size as the tank ! Swap that one

Ah sorry, mine is the one on the right! I had them in the same bucket after I fished out all of the fish from my late friends tank. I'm aware of the common pleco's fully grown size and noped out of that one!

 

I think the best option would be tocompletely rehome the lemons, 1 school of fish is enough for a 20 gallon, you could lrobably add a few kore cpds aswell. Maybe get another 20 and put in the lemons with a bigger school

 

I think for the 20 gallon you should keep one school of fish, probably the lemons. For barbs I have had success by adding more of the same species and females, the aggression has reduced by a lot. Only until feeding time, they go crazy haha. Like all the posts above, you should rehome your pleco. Pet stores usually give false information and state that plecos can live in small gallon homes, but they grow over a foot long.

 

I think the best option would be tocompletely rehome the lemons, 1 school of fish is enough for a 20 gallon, you could lrobably add a few kore cpds aswell. Maybe get another 20 and put in the lemons with a bigger school

Just found out I might be able to get a 30g or close to it sooner than I thought, do you think that would be sufficient space for the current inhabitants? Or would bigger/two tanks be the better route?

The Galaxy raspboros don't seem to be intimidated by the tetras, which I was worried about initially, I even see them swimming and schooling together occasionally. When the tetras are grumpy, the raspberries just chill at the back together.
The honey gouramis seem to be just big enough that the tetras have a healthy bit of fear of them, but they don't seem to know their own size. They're all getting used to each other, the male doesn't really give two hecks about anybody but occasionally the female and she just spends a lot of time happily examining every nook and cranny doing her own thing anyways, so they seem to coexist well enough.
The pleco spends most of his day on the underside of a piece of wood, but his much larger size deters anything from bugging him. He's a gentle giant.
In short, I think all the inhabitants vibe well enough together that with time and more space they could get along. But I have no experience to base that from, just my limited observation so idk

I think for the 20 gallon you should keep one school of fish, probably the lemons. For barbs I have had success by adding more of the same species and females, the aggression has reduced by a lot. Only until feeding time, they go crazy haha. Like all the posts above, you should rehome your pleco. Pet stores usually give false information and state that plecos can live in small gallon homes, but they grow over a foot long.

The pleco on the right is mine, not the common one! Do you know if the one I have will get bigger? Not sure what type it is.

For the Lemons, the ratio is 2 males/7 females. Does that seem right?
I think they might be ready to mate, I feed live worms or insect larvae/frozen bloodworms mostly and I've noticed the males colouring has gotten very prominent. Also some weird behaviour

 

The pleco on the right is mine, not the common one! Do you know if the one I have will get bigger? Not sure what type it is.

For the Lemons, the ratio is 2 males/7 females. Does that seem right?
I think they might be ready to mate, I feed live worms or insect larvae/frozen bloodworms mostly and I've noticed the males colouring has gotten very prominent. Also some weird behaviour

If you want them to breed it wont work in the community tank, you will need a seperate tank or tub.

 

Ah sorry, mine is the one on the right! I had them in the same bucket after I fished out all of the fish from my late friends tank. I'm aware of the common pleco's fully grown size and noped out of that one!

The one on the right also is a bigger type of pleco. I meand that one.

 

If you choose to keep your albino bristle nose pleco the 30 gallon will be better. You need to up your filtration quite a bit as these plecos are major poop machines. Elbert, that handsome fellow over there in my avatar is 5 years old and is about 6 inches long. Yours should get at least that big. He is in a 55 gallon tank with 2 HOB's rated for 100 gallons each and 2 dual sponge filters running in it. I change out 50% of the water every week.

You can never add too much filtration to a tank. To much water movement yes, but never too much filtration. Run the filter you have now plus a much bigger one on the 30 gallon when you get it. A heavily stocked tank is doable as long as you have enough filtration and you keep on top of the weekly water changes.

Your Tetras may be fine once in a bigger tank. You really won't know until you try though.

 

I've got 20 young lemons in a 55G. They're some of the more active tetras I've ever seen. Very cool little fish, but they seem to do everything a little more, a little faster than other tetras I've kept. Voracious little eaters, remind me of little piranhas. I'd worry about how a shoal of 2" long, fully grown lemons would do in a 20 gallon.

 

Thanks for the response!
I'm actually not sure if what I have is a pleco, I got it from my friends goldfish tank when he died so there's a chance that it's growth was majorly stunted. Not sure if it will recover from that..? I will re-home him though if you think that is the case.
What size tank would you recommend for the Lemons? I read 10g is the minimum size, but after seeing how my relatively small school behaves in 20 (and this was even when they were the only inhabitants in the tank), I feel like they'd need at least 30g looooong
In any case, I do plan on upgrading my tank, but unfortunately that's not an option until I'm able to move (which is difficult with covid). Do you know any way I could make the tank more comfortable for them/their tankmates temporarily? (Like ideally upgrading next month but realistically could be a couple months).

[In terms of tank health, I notice a lot of poo lol so I gravel vacuum and 20-30% water change every couple days, plus I have a 30g rated HOB filter, so hopefully that helps mitigate some of the environmental issues arising from the many inhabitants]
[Also more plants are going in today]View attachment 692836
View attachment 692825

I'm not entirely certain which species the one on the right is but it's definitely on of the larger types, possibly an albino common. It should grow to at least a foot long, even if it's currently in too small of a tank. Long term it will need a 180 gallon+ tank so it would be best to rehome it as soon as possible.

Just found out I might be able to get a 30g or close to it sooner than I thought, do you think that would be sufficient space for the current inhabitants?

Try to get as long a tank as possible. Bare minimum 30" for the lemon tetras. I would start by moving all the fish to the 30g and adding a few more tetras. If it still isn't working out you could move the CPD and honey gouramis back to the 20 gallon to allow for more space for more tetras.

 

The one on the right also is a bigger type of pleco. I meand that one.

Ah I see what you mean, I will re-home it then. Can you tell me what type it is? I've been trying to find out without much success

 

Maybe just a common pleco like the other one (except albino). I agree that it doesn't look like a bristlenose cat.