Adding large number of fish to new 6ft aquarium - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 4 Old 07-05-2015, 07:04 AM Thread Starter
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Question Adding large number of fish to new 6ft aquarium


In the near future I will be purchasing a 6ft tank & cabinet, and would like to start a planted freshwater tropical community aquarium. I have never had an aquarium before.

I intend to cycle the tank using household ammonia, as I have heard this recommended elsewhere. After it has cycled, I would like to add several fish at once (I intend to do a large order from an online fish store). My first fish will mainly be rainbows, and I would like to put in 15-40 at once (all between 3-6cm in size), but I am worried that this will significantly disrupt the nitrogen cycle.

My question is, can I successfully add this number of fish if I first cycle the tank with more household ammonia than would generally be used, and if so, how much ammonia would you recommend to adequately prepare the tank for this number of fish?

Thank you so much!
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post #2 of 4 Old 07-05-2015, 09:36 AM
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Hello and welcome to the forum

You will probably have an ammonia spike adding all of those fish at once but plants will be very helpful as they will use ammonia directly.

Test your water frequently and you might want to do daily water changes accordingly to keep levels down.
And I would strongly suggest using Seachem Prime water conditioner at double or even triple doses to lock free ammonia into less harmful forms for fish during ammonia and nitrIte spikes.

The good news is that under optimal conditions, your beneficial bacterias will double fairly quickly - 15 to 20 hours or so (don't hold me to that exact number) so as long as you keep up with the water changes and stuff a good amount of ammonia sucking plants into that tank, you should be able to keep your fish out of danger.

Good luck and keep us posted.

Animal testing is a terrible idea; they get all nervous and give the wrong answers.
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post #3 of 4 Old 07-05-2015, 06:26 PM
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Hi Rathacat and welcome,
Exciting times are ahead with a six foot tank. I'm glad you asked the question before going all in.
If I was in your shoes (wish I was) I'd check the local water supply and confirm the general levels of ph, gh and any nitrates. I'd recommend using a liquid test kit like API freshwater.
This information will make it easier to select plants and fish that will suit your water parameters (as apposed to backward engineering to fix the water after you have planted and added fish)
I would then fully plant the tank with your selected species and give two weeks or more for the plants to acclimatise, and also for you to get used to daily fertilisation routines for the plants, and again give the water time to settle. More research from you to considered is lighting requirements, photo period, are you injecting co2...... Stuff like that.
With the plants settled and showing growth, I would consider adding the fish. A six foot tank that is planted, should not require ammonia supplementation when adding fish, the plants will readily use the ammonia generated by the fish and the volume of water should reduce any initial spike (ammonia and nitrites) to levels that should be manageable.
IMO that is not a green light to add forty fish in one hit, I'd consider generating a stocking plan where you add say at max 15 fish per week. This will also reduce the shock on the system and allow for things to progress. And build your confidence in the daily,weekly maintenance. I'd really hate to see anyone fork out lots of money on fish for the system to crash and all the initial work goes to waste.
For a overall stocking plan can I suggest AqAdvisor - Intelligent Freshwater Tropical Fish Aquarium Stocking Calculator and Aquarium Tank/Filter Advisor. It is a really good guide and allows you to play around with the fish figures with your tank and filtration.
Remember, research research and research. Another common trend is putting incompatible species together.
But that's enough from me, enjoy the process as it will be rewarding in the long run.
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post #4 of 4 Old 07-08-2015, 05:47 PM
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I concur.
With fast-growing plants (floating plants, or stem plants if you have the light.. Hygrophila Diffirmis, Ceratopteris, Anarchis come to mind as stem plants- they can also be left floating if you have less light) and the rest of the tank well planted, no need for a cycle. Obtain a plant fertiliser called 'flourish comprehensive' and a water conditioner like Prime that detoxifies ammonia.

Plant a lot of varieties of plants, dose with flourish as per directions, and add your fish. Same day. The plants will take up all the waste from the fish. Feed the fish very small meals, whatever they can eat in a couple minutes, once per day for the first week.

Of course, this is assuming your water is good for rainbows, and your light is good for plants.

Originally Posted by Christople View Post
^^ genius

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adding fish , cycling , new aquarium , new fish , nitrogen cycle

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