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90 gallon, new fish?

Leopold

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Hello. I have a 90 gallon tank with one bristlenose, one synodontis catfish (about 6 inches) and one discus. The discus is happier alone, fights with other discus, but not other fish. I want to add more fish to the tank and I am thinking of two options:
1. 15-20 emperor tetras and 3-6 swordtails,
2. 15-20 emperor tetras and 6 congo tetras.
Which option would be better and is that too much fish in the tank? And if it's too much how many of each can I add?
Thanks
 

PheonixKingZ

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JuiceBox52

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Hi, I am assuming your water is soft based on the stocking you currently have, going off of that assumption I would do the tetras but not the swordtail because swordtail are hard water fish :)
It all depends on what your GH (General Hardness) is and is your water is soft or hard. Do you have a GH test kit?

It also depends on if the tank is fully cycled or not. have you read about the nitrogen cycle? If not, read up on this thread: https://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/
I believe it is cycled as the OP already has fish and I believe has had them awhile
 

PheonixKingZ

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I believe it is cycled as the OP already has fish and I believe has had them awhile
I complete newbie at fish keeping can buy a 90G, fill it with water and stick fish in it. It doesn't mean its cycled. If @Leopold didn't say his tank is cycled, or is he didn't say he knew about the nitrogen cycle, we can't take the chance. :)
 

Retired Viking

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Hello and welcome to the forum as the other members have brought up. Is your tank fully cycled, is you water soft or hard are basic question we need to know to accurately help you pick the right fish. We also would like what the PH level is and the GH (general hardness) You can get this information from your local provider.
 

Retired Viking

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90 Gallon tank is larger than the normal tank we help with. Could you give us the dimensions of the tank? Are these all the fish you are thinking of having? Sorry for all the questions but it is how we learn what you need.
 
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Leopold

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It all depends on what your GH (General Hardness) is and is your water is soft or hard. Do you have a GH test kit?

It also depends on if the tank is fully cycled or not. have you read about the nitrogen cycle? If not, read up on this thread: https://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/
Hello and welcome to the forum as the other members have brought up. Is your tank fully cycled, is you water soft or hard are basic question we need to know to accurately help you pick the right fish. We also would like what the PH level is and the GH (general hardness) You can get this information from your local provider.
90 Gallon tank is larger than the normal tank we help with. Could you give us the dimensions of the tank? Are these all the fish you are thinking of having? Sorry for all the questions but it is how we learn what you need.
My tank is fully cycled and has been working for years. Unfortunately I don't have any tests kits at the moment so I can't measure neither ph nor gh. The last time I measured the ph it was 6.7. About the general hardness, I have filtered underground water, so i can't really call a provider, but I know it's on the slightly softer side, it has a bit of iron in it. My fish never had a problem with it. It is a corner tank (quarter cylinder), the height is 23.62 inches, the radius is around 33.92 inches. I know I definitely want emperor tetras, but for the other I am open to suggestions.
 

Byron

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My tank is fully cycled and has been working for years. Unfortunately I don't have any tests kits at the moment so I can't measure neither ph nor gh. The last time I measured the ph it was 6.7. About the general hardness, I have filtered underground water, so i can't really call a provider, but I know it's on the slightly softer side, it has a bit of iron in it. My fish never had a problem with it. It is a corner tank (quarter cylinder), the height is 23.62 inches, the radius is around 33.92 inches. I know I definitely want emperor tetras, but for the other I am open to suggestions.
We can use the pH of 6.7 to assume softer rather than harder water, so swordtails (and any livebearers) are not going to work. The characin group (tetras) is a good option from the aspect of parameters. These are shoaling fish, and the larger the group the better they will be, and you have space here. The 15-20 Emperor Tetra is good from this perspective, but the Congo Tetra is not; a group of 10-12 with roughly 50/50 male and female would be much better. I had ten (50/50) in my 90g for several years.

Another issue though is the poor discus. I understand the issue here, but the question becomes how this fish will be perceived by some species. i don't expect you would see any issue with the Congo Tetras in a group of 10-12. The Emperor Tetra is a very different thing. I had some real aggressive issues with this species, and given this plus the general advice that the species can be a bit more boisterous (rough) than many other tetras, I would look at other species. Of course, another unknown is the discus' attitude if groups of tetras enter "his" (or "her") space.
 

Retired Viking

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I have a 55 gallon tetra tank , I would think it would be awesome to have a 90 gallon tetra tank. If you like small shoaling community fish most tetra species are great. But like @Byron pointed out there are some that have issues. My favorite is my glow light tetra. They tend to stick together and it is interesting to watch them swim as a group.
 

TekFish

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If you have soft acidic water PLEASE South American Biotope. Those tanks are gorgeous and so interesting! And in a 90G??? Man, you could have an amazing setup... You could have angels, with fuller-bodied tetras, or smaller tetras with SA dwarf cichlids, Corydoras, Otocinclus. It's one of my favourite tank setups.
 

Metalhead88

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If you plan to keep the discuss, I'd recommend trying your hand with more discuss once again.

Other good options I'd recommend (I have a 90g with very similar ph and I'd assume hardness as well) are a fully stocked Angelfish tank OR

As I have done, a south american cichlid tank. I have a few cichlids and a nice school of giant danios (rainbows would work as well) It's an awesome tank.
 
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Leopold

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We can use the pH of 6.7 to assume softer rather than harder water, so swordtails (and any livebearers) are not going to work. The characin group (tetras) is a good option from the aspect of parameters. These are shoaling fish, and the larger the group the better they will be, and you have space here. The 15-20 Emperor Tetra is good from this perspective, but the Congo Tetra is not; a group of 10-12 with roughly 50/50 male and female would be much better. I had ten (50/50) in my 90g for several years.

Another issue though is the poor discus. I understand the issue here, but the question becomes how this fish will be perceived by some species. i don't expect you would see any issue with the Congo Tetras in a group of 10-12. The Emperor Tetra is a very different thing. I had some real aggressive issues with this species, and given this plus the general advice that the species can be a bit more boisterous (rough) than many other tetras, I would look at other species. Of course, another unknown is the discus' attitude if groups of tetras enter "his" (or "her") space.
Thanks for the advice about the congo tetras. I understand the concern, but I'm not that worried about others trying to nip at him (the discus name is Leopold, it suits him). Because of one time I put about 20 small (~1 inch) convict cichlids with him (didn't have anywhere to put them for a week). They avoided him like the plague and swam around him in a circle, so I'm not worried about Leopold holding his own. This all happened before I moved him to the 90 gallon, he was in a 30 gallon before. I am hoping that with more space he will be a bit less territorial. How I would describe him: I like you as long as I can't eat you and you aren't prettier than me. If you don't touch me, I won't touch you, most of the time. Knowing Leopold it's kind of a plus that emperors are more on the rough side considering their size.
 
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Leopold

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I have a 55 gallon tetra tank , I would think it would be awesome to have a 90 gallon tetra tank. If you like small shoaling community fish most tetra species are great. But like @Byron pointed out there are some that have issues. My favorite is my glow light tetra. They tend to stick together and it is interesting to watch them swim as a group.
I like small schooling fish, but because of the discus can't add them. My first try was zebra danios, my mistake was not putting in fully grown fish. The second try was silvertip tetras. In both cases he ate them. The small danios within 2 days, the silvertips within 2 weeks. What I've learned: anything smaller than an inch will be eaten instantly and anything smaller than 2 will be eaten one by one with time. So I'm looking for tetras 2 inches and above. And unfortunately almost all my favourite schooling fish are too small. If I add emperors, I will add only fully grown fish.
 
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