Number of fish to add at one time

[Jess]

I have a 60L (17 gal) heavily planted tank, fully cycled and running for two months with just the hitchhiker bladder and ramshorn snails. I don’t feed it; it has ADA Tropica aquasoil (which releases ammonia), plus poop from a million snails keeping the bacteria colony going.  I am adding a group of 6 Parosphremonus phoenicus (0.5-1” in size now), and I also want to add a school of maybe 18 chili rasboras. 
 

I’ll get at least the P. phoenicus from The Wet Spot (I live on East Coast so I can’t get from Cory) because they have lots of them. They also have the chilis. The shipping is $40, and I’m told if my tank is cycled it’s probably ok to add them at the same time.  Of course, I’d feel more comfortable adding one group and then the other. But if it’s likely safe to add both, I save $40 on shipping.  
 

I’ll do what’s best for the critters over what’s best for my pocketbook (haha), but would like opinions from the group about whether I’m being unnecessarily cautious or whether it’s probably ok to add both together.  I’ll be feeding BBS because the licorice gouramis only eat live foods. 
 

My pH is 6.0-6.2. One of my concerns is that maybe the bacteria are not as robust at this low pH.  
 

As always, thoughts and advice from the more experienced fish keepers are welcome. Thank you all!

[Brandy]

Because of the very low ph any ammonia will not be as toxic for your fish. However, because of the low pH you may have to aclimate your fish slowly and carefully. I would test the water in the bag, and aim for a midpoint if possible. 

Normally I would say go slowly with the fish, add the two groups about 2 weeks apart.

Alternatively, in this situation get both and try to feed lightly to begin with. The bacteria will increase to fit the load and the load comes in from the food, not the fish (unless they die and then it comes from the fish body directly). You can jumpstart the process by feeding the tank a small amount now, and watching your parameters. the amount you can feed today without an ammonia spike is how much you can feed, no matter how many fish you have. Tomorrow you can feed a bit more, etc.

[Nana Finopolis]

I did something similar recently. I have a 40 gal. breeder. It is pretty heavily planted. One big difference is that i changed the substrate. I added 20 ember tetras and 10 cories. It previously held only 6 cardinal tetras. I did get a rise in ammonia. I've been doing frequent water changes, double dosing Prime and only feeding every other day. You can probably get away with it but watch your water parameters really close. I am still checking ammonia daily just to be safe.

[Jess]

Thanks to you both!  I will definitely take this advice. I work from home now, luckily, so I can test multiple times during the day. I have Tetra and API, so I have “backups.”  I have Prime too, in case I need it. And I will go ahead and prep some water for water changes too. 
 

I also still have FritzZyme 7 in the fridge.  Would it be helpful to add a dose?  If so, when? Before the fish arrive?  

[CanadaAmanda]

A cycle is not on/off but rather scaled to the bioload it supports.  You have a tank with enough bacteria to process the waste of the snails, that's it.  You will be going through another cycle, to catch up to the new bioload, when you add fish. 

[Brandy]

@CanadaAmanda is right, but you won't be starting from scratch--you have a seeded tank.

I recently filled a tank an put in 3 fish in the same day, I had a pre-seeded sponge filter from another tank and I fed lightly at first. No issues at all. Then a few weeks later I dumped in about 30-40 guppies. I didn't feed for 3 days, then fed very lightly. I got a bacterial bloom for a day or two, but again, no problems with the fish, no obvious ammonia spike. It is much less scary once your tank has bacteria in it. 

 

[Jess]

Update: I added 6 licorice gouramis and 12 chili rasboras to my 17 gallon planted tank two days ago and everyone is doing great.  I'll be doing a 15% water change today, but so far everything is great.  I wanted to upload a picture here but it uploads upside-down and there are no forum options to rotate it.  (Rotating the pic on my hard drive didn't help; it uploads upside-down no matter what I do).

[ChemBob]

23 hours ago, Jess said:

Update: I added 6 licorice gouramis and 12 chili rasboras to my 17 gallon planted tank two days ago and everyone is doing great.  I'll be doing a 15% water change today, but so far everything is great.  I wanted to upload a picture here but it uploads upside-down and there are no forum options to rotate it.  (Rotating the pic on my hard drive didn't help; it uploads upside-down no matter what I do).

I've had the same picture problem. Never been able to figure it out. I just upload anyway. The way I figure it, and upside down picture is better than no picture.