Tetras how many? - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 5 Old 06-09-2019, 11:13 PM Thread Starter
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Tetras how many?

Building a 55 gallon Tetra only tank. I have a lot of years with tropical fish but never 1 type of fish all were always mixed stock. I have had usually large tanks over
75 gallons. I will have plenty of filtration upwards of 600-700 GPH and flow adjustable so not to stress out the fish. QUESTION IS how many Tetras will a 55 handle safely. I always do every week at least 30 to 35 gallon water changes.
All feedback greatly appreciated

Thanks Bill

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post #2 of 5 Old 06-09-2019, 11:43 PM
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Depends on what kind of tetras you're considering!

Luckily, I believe every kind of tetra is both peaceful and schooling, so you shouldn't have to worry about fish getting territorial. Keep in mind that I do not personally own tetras, this is mostly from general knowledge and a fair bit of googling. And, although the 1 inch of fish -> 1 gallon of water rule of thumb is really flawed, it can work well for smaller fish. Always always always lean towards the lower end if you're unsure. It's very easy to overstock a tank (even with powerful filtration), and very hard to understock.

Other consideration is how heavily planted your aquarium will be, temperature, and temperament of the fish. Most tetras will want lots of hiding places, so if you're planning on a sparser tank, plan accordingly. If your fish want to all be hiding at once, that should ideally be possible, though in larger schools they should feel confident and rarely hide. Let's get to numbers:

The most popular tetras, neons and cardinals, are both small and hardy, so you could probably get away with about 1 fish for every 1.25 gallons, or about 40 fish. Less so for cardinals since they get just a bit bigger, the most I would go for them would be about 30.

Black skirt tetras, another classic, get about twice to three times as large as neons, so I would stick to less than 20.

Serpae tetras can apparently get fin-nippy if they're stressed or crowded, although I don't think they nip at other tetras of their own species. Still, I would lean towards less fish rather than more, maybe starting with 20 or so to see if they're happy like that.

Good luck, and please remember to start with a smaller number if you're unsure! Tetras are beautiful in all their kinds and I'm sure you'll have a wonderful time with it.

P.S. 30-35 gallon water changes from a 50 gallon might be too clean. Beneficial bacteria still has to grow, and if you have to change the water that thoroughly to keep clear water/algae contained/healthy parameters, there could be other underlying issues like un-neutralized ammonia in your source water or too much light.
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post #3 of 5 Old 06-10-2019, 12:09 AM Thread Starter
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I thank you for your response. The tank is a Aqueon 55 gallon. I only said 30-35 gallon water changes because that's what I did with my big tanks especially the Cichlid tanks. Had a 140 gallon with a sump filter had to have plenty of filter for those Cichlids. Beautiful fish constant up keep. I figured about 30 to 35 fish it should handle that amount. I will not do a planted aquarium never done one. I will have a black back ground and black substrate. That should make them stand out pretty good. Thanks again for your feedback


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post #4 of 5 Old 06-10-2019, 11:40 AM
I would sit down and first decide on the type of tetras you want. Start building one school at a time and see how the tank balances it. Layout, planting, and current all factor into the amount of fish. O2 levels might be more of an issue with bioload fyi
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post #5 of 5 Old 06-10-2019, 01:54 PM Thread Starter
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Hi Genos; I do under stand keeping the tank in balance. Over lots of past years having (30) aquariums I was very lucky keeping all my tanks balanced. My biggest tank was a 140 Chiclid tank with sump filter system. I did at one time have 3 125 gallon fresh water tanks all mixed fish all tropical. This new 55 gallon I can handle at 79 years old. I was in the USAF for 20 years. I was at one base over 12 years and then we were assigned to Germany. When I came back started all over again. This is my main hobby. It will be fun to get back in to it after a short spell. I learned long ago about over stalking and to keep a balanced tank. I always start with 6 to 12 small Tetras wait for the tank to balance. I am hoping to do at least 30-35 of the smaller Tetras. Time will tell where that number goes. I really appreciate your feedback it all counts.

Thanks again Bill

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