Danio Fry Growing Issues, Please help!

TheFishoftheSea

In October, my Danio's unexpectedly bred in a 2.5 gallon tank. There were about 100 fry or more. When they started to get bigger I had to purchase a 10 gallon. I moved some of them into that tank yet they did not grow nearly as fast as the ones in the tank that they were born in. I moved those fry back into the same tank as they were born in. Some of the fry were getting big but some, I am assuming the ones that had been moved from the 2.5 to the 10 and back to the 2.5, weren't growing fast or at all. Some a little bigger and some are the same size as when they were born pretty much. Because they were getting bigger I separated them all into three separate tanks, each 2.5 gallons, I also made sure that some of the original water they were born in went into them. But they are all growing either not at all, extremely slowly, or bigger but aren't growing as fast after the move. I am very worried that they won't grow. This leads me to a couple questions:
1. I shouldn't have moved them in the first place, right?
2. I am feeding them grinded up flakes, the same that their parents eat but obviously smaller, which they are eating by the way, is that ok though? Should I get something different to feed?
3. Is there anything I can do to help their growth?
4. Will they grow bigger overtime? If so, what is the best way to speed up the process.
5. I have filters for the tanks that the fry are in, but I removed them because they are to strong. Should I put a filter in the tanks though? If so what is a gentle filter that the still very small fry won't be pulled into.

I am very new at raising fish, although, I have owned fish for many years (this has never happened before). I really love my fish and I do want to continue in the breeding hobby. I guess this is just a learning experience. I still want to make this group of fry better. Your help is much appreciated.

Here is a video of the good tank were the fry are better. Not all of them are visible in the video but there are way more.
The Larger Fry: file:///C:/Users/elisa_hr779o6/Downloads/VID_20211201_220837065%20(1).mp4
 

Flyfisha

Hi DaughterofGod17
I have raised a few fry but my climate is a little warm for danios so not that species.

A couple of things I was told but found hard to believe. I tell you because you are seeing for yourself what may be the same issue?
Fry release a growth hormone that stops other fry growing. As strange as it seems it’s true. Perhaps it has something to do with natural limits on a species in times of drought?
Anyway I have proofed to myself beyond any doubt that regardless of the volume of quality foods provided including live foods only multiple water changes each week give fast growth.
We can’t measure hormones with our test kits.
I have found up to three 45% water changes but a minimum of two 45% water changes are needed for all fry to grow in almost any stocking of tank. Definitely in the size of tanks you are working with. Perhaps even more important in the 2-5 gallon?
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In an idea world all fish should have a cycled filter. They should at least have an air stone offering maximum oxygen if they have no filter. See 5 gallon buckets of fry on floor. Sorry fish police about the no filter but they are getting water changes often.
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To answer your question.
#1
Moving fish is normal and very necessary.Moving fish will not stop or slow growth.

#2
Using different brands of adult foods crushed to dust might provide something missing in one brand. Fry should get good quality (expensive )foods but it can be just adults food crushed to dust.
#3
Lots of water changes make an unbelievable difference in growth.
#4
It is possible to stunt fish but hopefully it’s not to late for them to have a growth spurt.?
#5
Unless you have only half a dozen fry in a 5 gallon bucket they really do need a cycled filter . They will need one soon or you will get sick of water changes every 48 hours.

Fish that make copies of themselves is a great part of the hobby. It’s all a learning experience for everyone.
 
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TheFishoftheSea

THANK YOU THANK YOU! This is extremely helpful! Do you think that I should get a larger tank to combine all of them in? I think there are about 100 divided into two, 2.5 gallon tanks. Obviously that is not healthy. Also, will they ever get bigger or will some just stay that size? I am very afraid that they won't grow and I will be stuck with almost microscopic fish.
 
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Demeter

Once given proper care a lot of stunted fish come around and grow properly. Some may always be smaller than they should be but that's okay.

As stated previously, bigger tanks and lots of water changes are key to growing strong young fish. Cycled sponge filters are also great to have, I use them in several of my fry tanks.

One thing to keep in mind, unless you have someone to take fish off your hands, do not bother trying to save every egg/fry born in your tanks. You will quickly become overrun with fish, crowded conditions are not good to have fish in long term.
 
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TheFishoftheSea

Ok, I will try to make room in my room (my bedroom that has turned into a full on aquarium which wasn't supposed to happen) for a larger tank. What size do you suggest? Yes, I have only two people so far interested in them. I am considering posting on here, once they grow to a better size, that they are for sale. I will just need to figure out if I can do shipping or not.
 
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mattgirl

With that many fry in the size tank they are in I highly recommend changing out no less than 50% of the water every day. Flyfisha is absolutely right.about the growth hormones. We have to keep them diluted or some of the fish will not grow.

As Demeter pointed out. Once you start doing the water changes the smaller ones may start growing. Only time and fresh water will answer that question.

I highly recommend you run a sponge filter in this tank. A HOB with a pre-filter sponge would work but with these little guys a sponge filter will work well. Many years ago I ended up with bunches of zebra danio fry. The store I sold them to only paid .25 cents apiece for them and I considered that a fair price.
 
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TheFishoftheSea

Wow thank you so much mattgirl! I will try my very best to do those things! Are you able to send me any links to good sponge filters that you recommend? Thanks!
 
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mattgirl

Wow thank you so much mattgirl! I will try my very best to do those things! Are you able to send me any links to good sponge filters that you recommend? Thanks!
You are so very welcome :)

Just about any sponge filter will work. Just recently I got some from aquariumcoop. Coarse Sponge Filter | Aquarium Filter for Fish Tanks | Fish Filter. I bought the nano and medium. For the small tank you are running either the small or nano should work well.

I have also used and am happy with the double sponge filters I bought from a seller on ebay. 4 PCS Bio Double Sponge Filter Betta Fry Aquarium Fish Tank XY-2831 | eBay I have bought items from this seller lots of times and have been satisfied with my purchases. If you don't already have a pump and the items needed to run the sponge filter this same seller has everything you need in stock.
 
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