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Adding Fish

Banafish

Fish Fanatic
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Hi, after cycling my tank, how many species of fish can I add at once? All at the same time, or one at a time? Thanks! I am planning to keep 10 Neon tetra and 3 guppies.
 
Depends on the size and parameters of your tank tbh. I've seen youtubers add anything and everything all at once but from what I have read it's easier on the bioload of the tank to add one species, wait a few weeks, then add the next.
 
This is something that im starting to think about, my tank is also in the cycling process. Im looking at around 20 fish in my tank. Im going to start with the neon tertras.
I also want a betta amongst about 6 other varietys (that will all get along of course)
Just not sure when exactly to add them or if theres an order?

My tank is 160 litres does this affect anything?
 
One of the major benefits of a fishless cycle is that one ends up with a tank cycled to handle a full fish load. By adding fish gradually you actually un-cycle the tank a bunch and turn it into a fish-in cycle.

The bacteria reproduce more when there is more ammonia than they need to thrive, this also implies there is more nitrite as well. The bacteria will keep reproducing at a rate higher than they are dying. This results in the colony getting larger until it is in balance with the ammonia being created. This works in the other direction as well. If there is not enough ammonia to support the existing colony, reproduction slows so that more individuals are dying than are being "born," and the size of the colony shrinks.

Over time the amount of bacteria will always adjust to the ammonia load. At the end of a fishless cycle, it is the fish which we add to the tank which becomes the major source of ammonia being created.

One last observation about the timing on stocking. When talking about stocking slowly or gradually, there is a difference if one means they will be about fully stocked in a week or two v.s. it will be a couple of months. Individual bacterium are dying and others or being born. This means 3 conditions are possible in response to the ammonia load in a tank.

1. During cycling there is more ammonia than the bacteria can consume. So the birth rate accelerates and more bacterium are created than die.
2. Once the Bacterial colony has enough number to handle the ammonia being created, reproduction and death rates will be about equal as long as the ammonia level is maintained.
3. If the ammonia kevel being created is reduced, the there will be more individual bacterium dying than are being "born." The result is the bacterial colony will shrink until is is in balance with the lower amount of ammonia being created.

Of only things were just this simple. They are not. Most experienced fish keepers have learned to Quarantine new fish for some time before adding them to an established tank. This avoid adding a disease to tank the new fish could have but not yet show and symptoms. In the case of a brand new tank being stocked, all of the fish that go into together in the initial stocking are essentially in a Q tank. Fish to be added later should spend time in a Q tank before being added to the main tank.

Most of us, myself included, had no clue about the need to quarantine until we had been in the hobby a while. We usually needed somebody to explain this. So this is another reason to consider a stocking plan to get many of the fish into the tank after completing a fishless cycle as one can.

If you need to wait a bit to put it sll together you can keep the tank cycled by adding the same full dose of ammonia you used toduring the cycle every other day. You will also need to change water weekly to hold down nitrate. but you can hold a cycle this way for weeks if necessary. (Obviously, there should not be any fish, shrimp or beneficial snails in the tank if one is doing this.)
 
My tank is 52l. Thanks!
Hello Bana. This is a very small tank. Properly acclimate half the fish and then set up and follow an aggressive water change routine. A tank this size is going to be a challenge to keep the water clean enough all the time for the fish. I would remove and replace half the tank water every three to four days and allow the tank water to settle with just half the fish. After a couple of weeks, you can add the rest of the fish. Continue to follow your water change routine for as long as you have the tank running. Feed just a small amount of a combination of flakes, freeze dried and frozen foods. With such a small tank, you won't have the luxury of missing even one water change. A larger tank would allow more room for a mistake in tank management.

10 Tanks (Now 11)
 
If you did a fishless cycle and had the ammonia level around 3ppm, then you can add all the fish at the same time.

Neons and guppies require different water chemistry.
What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.

If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.
 
If you do what 10 Tanks suggests, be careful. He is suggesting that you to double the bio-load in a single go. I would not advise that course. If you decide to try this, make sure you test for ammonia 2 -3 times a day after adding the second load. You should for sure see an ammonia spike. My normal advice would be 1/2 the bio-load in then 1/4 and then the final 1/4. But, as I stated in my initial post, I would add them all at once.

If you do decide to do what 10 suggested, then I would for sure use a Q tank on the 2nd half of the fish to be safe. I normally Q new fish between 30 and 90 days- 30 for farmed/tank raised fish and 90 for wild caught. Those times are for consecutive days without any issues. If I have to treat fish in a Q tank, after they are cured, if they are, the Q time starts over. Quarantining new fish protects your existing fish from being infected by introducing a new fish which has an issue/issues. A lot of the diseases we end up having to fight come in undetected with new fish. I have some fish for close to 20 years and I an not willing to rise them for the sake of getting something new.

Most local fish stores and pet stores are not great on keeping their tanks healthy in terms of incoming new srtock. Ideally, they want to sell a fish 5 minutes after they get it. Very few of them quarantine new stock for any time at all. The problem is it can take days or weeks for problems to show symptoms which let us know there is an issue. I have only had Ich twice. Both times it came in with new fish and neither time did the fish show any white spots at the time of purchase or for a day or two thereafter. And then it hit hard and spread to the rest of the fish in the tank. One time I skipped Q and I lost both the new fish and some of my existing fish. The second time I used Q and lost all of the new tetras and all but one of the new danios. But I did not lose any of my existing fish in established tanks.

All of the above said, I also strongly agree with 10 when he observes that you really should have a bigger tank than 52l if possible. Bear in mind that you are new to all of this and that 10 has much more experience. While 10 would do what he advises you to with no problems, you might run into a few. Hopefully, the longer we are in this hobby, the better at doing it we all get.
 
It also sounds as if 10 Tanks is referring to a fish-in cycle rather than fishless.
 
Hello. The poster is talking about a 12 gallon tank and 12 small fish. If the poster follows my advice and changes most of the tank water every few days and feeds sparingly, the toxins produced by a few small fish can easily be removed well before they build up to anywhere near problem levels.

10 Tanks (Now 11)
 
Hi, after cycling my tank, how many species of fish can I add at once? All at the same time, or one at a time? Thanks! I am planning to keep 10 Neon tetra and 3 guppies.

Aside from the already mentioned issues, you have neon tetras which are a shoaling/schooling fish. The number of 10 is excellent. But they should all be added together at the same time. They will settle in much faster the more there are, which means much less chance of additional stress causing disease issues.

The guppies can be added together, though not strictly a shoaling species, it would be preferable especially if males (males only avoid regular fry which would quickly overwhelm this tank).
 
Hello-

1. Can you please explain why anybody who has done a complete fishless cycle and has a fully cycled tank which is able to accept a full fish load safely should do what you suggest? I do not understand the reasoning for going backwards. It means more work and more spending.

2. Can you please explain why one should ever do more water changes than are needed to keep a tank healthy? Water changes are a bit stressful for the fish, so why create more stress without good reason? I change the water in my 150 gal once a week, I change the water in my 5.5 gal. once a week. I change the water in the rest of my 20-26 tanks just once a week (I have done so for over 2 decades.). All the changes are at least 50% and more like 2/3 and many of the tanks are heavily stocked.

3. Can you please explain why you appear to think that think quarantining new fish before adding them to an established tank is not a good idea. Your suggestion sure creates a situation where it becomes a good idea. On the other hand, why is fully stocking the tank in one go with fish from the same store/seller is not a good idea since it likely avoids the needing to do Q in several weeks?

I am a big believer in the KISS theory and in Occam's razor. I always prefer to avoid making things more complicated than they need to be.
 
Can you please explain why you appear to think that think quarantining new fish before adding them to an established tank is not a good idea.
This is always a good idea if you have existing healthy fish in a tank. I made the mistake recently of not quarantining. The whole stock I bought died within a day and took a couple of my existing fish with them. Never again.
 
So are we suppose to quarantine the fish before adding them to a brand new cycled tank?
Say for example I buy 15 neon tetras as my first fish... Im presuming they dont need to be quarantined, as they have all come from the same place.

But say 10 days later i go and get my next fish, these would need to be quarantined, is that what your saying?
 
If they all come from the same shop within a short period of time, quarantine is not necessary.

When we have a tank of fish with the same fish for several months or years, if there had been any sickness in the tank we would have dealt with it and all the fish will be healthy. Then we want more fish. Those new fish could easily be sick in the shop and they'd give the disease to the fish already in the tank and potentially kill them. So we use a quarantine tank for the new fish and leave them in there long enough to find out if they are sick. If they are, we can treat the disease in the quarantine tank. Once we are sure they are not sick, or once sick fish have been successfully treated, we can then put them in the main tank and know they won't pass a disease to the fish already there.

When a tank has been fishless cycled and we buy fish from the same shop, if there's any disease they'll all have it since the disease will be in all the shop's tanks. We can put them straight into the cycled tank and if necessary treat them in there.
Then we want more fish. If we get them after just a couple of weeks from the same shop, they can go in the main tank. But if you get fish from a different shop, they might have diseased fish, you can't tell. So fish from a different shop should be quarantined before going in the main tank however long it is after you got the fist fish, a week or a year.
 

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