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Discussion Starter · #1 ·
How many fish can i add at once to a cycled tank?

Hi,
I have jsut finished a fishless cycle. At the moment, I can put in 3ppm of ammonia in the morning and by the afternoon ammonia and nitrites will register as 0.

How can I work out how many fish i can put in at once?.. or in other words, does anyone here know how much ammonia fish actually produce?

Thanks very much for any responses in advance.

Regards,
Ben.
 

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Discussion Starter · #3 ·
Thanks Mediahound.

The tank is 2.5' x 1.5' x 1.'5 (100L).

I want to be able to go to the fish shop and buy as many fish as possible at once (mostly because of my busy schedhule).

I am still tossing up between an african cichlid tank and a general community tank with tetras, catfish, maybe a dwarf gourami etc.

If i go cichlid, it will have a very light ammount of plants. If i go community it will start of lightly planted and then, as i teach myself, i will move to medium and hopefuly heavily planted with CO2 :)

I thought that bioload WAS the bacteria that eat the ammonia. Now im confused. I do have 'Cycle' and another 'bio boosting' product at home. Will these do?
 

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Water Chemistry/ LiveBearer Specialist
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If you have cycled the tank using an ammonia source and it is processing the ammonia to zero in less than a day now, you are ready to add maybe half of the final stock level all in one go. If you have just been using something like Cycle for the week they recommend, you are not ready for the first fish yet.
Cycling a tank takes time and some attention on your part, it is not truly done using silly things like Cycle. The bacteria need time to reproduce in your filter and need a food source, like pure household ammonia, to grow on. If you start with a concentration of 5 ppm ammonia and dose back up to 4 or 5 ppm whenever that concentration has gone to zero, you will eventually get to where the ammonia will be gone in 12 hours. If the nitrites are also staying at zero by then, you have something that you can work with to stock a new tank. More often, the nitrite converting bacteria will take a couple of more weeks to develop to that point ,so you will need to keep dosing ammonia while they develop. By the time your bacteria levels are well established, the nitrates will be completely out the top so a huge water change will be needed before you actually add any fish. Because the bacteria live on surfaces, not in the water, the large water change will not be a problem for the biological filter.
 

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Discussion Starter · #5 ·
FINALLY a proper answer!

I have posted this question in 3 different forums and you should see how many responses like "just start off with 2 hardy fish as the ammonia will spike" - completely not understanding the fact that i have already built up my bacteria using pure ammonia.

I didn't know i should do it at 5ppm per day though. I can currently add 3ppm of pure ammonia and it is gone in 12 hours, along with the nitrites (took 4 weeks to get to this point). So if you say i can half stock a tank if if i can get rid of 5ppm per 12 hours.. seeing as i can only get rid of 3ppm and cant be bothered upping it to 5ppm, i will 1/3 stock the tank.


Thanks very much for your help!! 1 question while i have you here.. Should i add say add the less agressive fish types before the agressive fish types, so that they can establish some territory/space and feel more comfortable, or doesn't it really matter because they can just get their territory/space stolen off them anyway...?
 

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My opinion as was stated above in any case. The tank is cycled to maintain the current bio-load, If you increase that load to quickly it could cause problems. This is a double edged sword so to speak, First most fish are somewhat territorial, so to stop any aggression or keep it to a minimum, it is best to add fish of the same general size,and temperment, at the same time so everyone has a level playing feild. But on the other hand too many at once could overload your system. Bottom line : I would opt for just a few at a time to allow the system to adjust slowly, and stick with juvuiniles which would limit aggression.
 

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A 100 litre tank should be able to handle about 30 inches of small fish in the short term, less than 6 months out. It will be able to handle more once everything has settled in well. The 1/3 stocking makes some sense to me so I would start with about 10 inches of fish which would be about 5 or 6 the size of a platy. It is best to start with whatever fish are the hardiest of the ones you will be keeping. That way any slight fluctuations in water chemistry can happen with fish that can handle it. Once the first group is settled in for a couple of weeks, try to keep each new addition to about 40% or less of the existing biological load. Theoretically the biological filter bacteria can double their numbers in about 24 hours but it would be a bit silly to make believe that the real world works that way so I suggest that a 40% bump at a time is all you should try.
 

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Discussion Starter · #8 ·
Thanks all for the excellent responses. After speaking to quite a few people now who fully stock their tanks after a fishless cycle using ammonia, i decided to push the limits a bit..

Yesterday, after a test to make sure that the ammonia from the last dosage had been consumed, I added to my tank the following (at 4:00pm):

3 x Endler Guppies (.5inch)
5 x Glass Tetras (the reeealy see-through ones) (1.5inch)
1 x Dwarf Honey Gourami (1 inch)
9 x umm i forgot what they are called.. tetra with neon red stripe through it (1inch)
1 x Red tailed shark ( 2 inches)

= 21 inches of fish (in a 30 gallon tank)

So i stocked it to 2/3 of its final stock list.

I checked ammonia levels this morning and they read 0.

Will test again this afternoon and will keep you all posted :)
 

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This is one thing to remember...The 1in per gallon rule doesn't apply if you will actually take care of the tank and have a community set-up. The only fish that you are strictly limited on are cichlids and aggressive fish.
This is how I justify this..I have a 10g tank with swordtails in it. The tank had 10 swords in it. Swords get 3in long, making my tank 3 times overcrowded. However, I have had them in this tank for over a year with no problems. I have live plants and I change 10% a week. This just proves that whole 1-1 ratio wrong.
The fish you all have are community therefore, you should be able to fit several over the limit quite comfortably. If you maintain, the tank you will be just fine. Good Luck, we hope to see picks soon!:)
 

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The 1" per 1 gallon is just a guide. However, someone like Eaglesfan above, can get away with overstocking because he also has live plants. Plants naturally convert ammonia, and nitrates to food so they help keep your levels low. People with a lot of plants actually have to add nitrates back to their tanks or "overstock" their tank to keep their plants healthy.

The other thing to consider is the type of fish. For instance a 1" neon tetra will eat less and make less waste than a 1" goldfish. You are adding a lot of ammonia, more than 2-3 fish make in a tank that size, so you should have no problems stocking that tank fairly full since you are fully cycled. However, keep in mind how big each type of fish will get when mature.
 

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Oh yes I had forgotten about goldfish. They go along a different set of lines as well. Thanks for pointing that out. The guide is for new aquarists who are just getting started with tanks. Once you get experienced, you can easily bend those rules without any troubles at all.
 

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2 to 3 at a time. The ratio of fish to water is 1 inch of fish to 1 gallon of water. Gold fish are different and need 55 gallons of water (for 1). Slim bodied fish are oppisite you can add 2 inches per gallon.
 
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