Hiya - Baby Zebra Danios Dying

[Joolz]

New to this fish keeping lark. Have had my 35ltr tank for around 4 months now I have zebra danios and platys with plastic plants and gravel and a filter. All very happy ? .
I rescued 5 baby danios from the community tank and set up a breeder box in the main tank with tights round so they wouldn’t get sucked out by the parents ? and fed these on first bites for a month and half then transferred them to new 12ltr tank for them to grow and have done 10% water changes in there with water from the main tank.
A couple of the baby danios didn’t make it which left me with 3 then the other day I noticed the tank looked like it had been invaded with what looked like cobwebs or white dust crap everywhere. I have a sponge filter in there and an air stone. So I took the decoration out that I put in there for them to be able to hide and switched the air stone off as I though it needed to be a bit calmer for them as two of them appeared to be struggling getting flung around with the currents. I am now down to one baby danio that is 2 months old who looks healthy but looks lost and lonely and am worried it won’t survive as they need to be in groups. I would appreciate any advice ?

 

[Andy Sager]

New to this fish keeping lark. Have had my 35ltr tank for around 4 months now I have zebra danios and platys with plastic plants and gravel and a filter. All very happy ? .
I rescued 5 baby danios from the community tank and set up a breeder box in the main tank with tights round so they wouldn’t get sucked out by the parents ? and fed these on first bites for a month and half then transferred them to new 12ltr tank for them to grow and have done 10% water changes in there with water from the main tank.
A couple of the baby danios didn’t make it which left me with 3 then the other day I noticed the tank looked like it had been invaded with what looked like cobwebs or white dust crap everywhere. I have a sponge filter in there and an air stone. So I took the decoration out that I put in there for them to be able to hide and switched the air stone off as I though it needed to be a bit calmer for them as two of them appeared to be struggling getting flung around with the currents. I am now down to one baby danio that is 2 months old who looks healthy but looks lost and lonely and am worried it won’t survive as they need to be in groups. I would appreciate any advice ?

Danios in general are very effected by water quality so I would not have used the main tank's water for water changes but used new water. You mentioned you did a 10% water change. How often? Daily, weekly, monthly??
The white stuff may be a phosphate dust coming out of solution. Hard to tell without test results.
With fish fry, there is a natural death rate. The formula is mostly 10% of a spawn survives to become breeding adults. So since you started out with only 5, the odds of survival were stacked against you, especially when Zebras average hundreds of eggs per spawn.
As for the remaining Danio, it's too young to be " lost" by being alone. At this age, you should be feeding it other foods besides the first bites. Try adding baby brine shrimp ( it comes frozen. Thaw before feeding.) or even Decapsulated brine shrimp eggs ( which are dry) to get the fish up to size quicker so that you can add the fish back into the main tank with the other Zebras. There are also some other nano fish and fish fry foods that will help grow the fish that should be incorporated into the fish's diet. Fish shouldn't be fed just one kind of food. Variety of ingredients is what helps keep them growing and healthy. Be mindful of water quality. Clean water is very important to growing fish. Change small amounts more often when the fish are young or larger amounts when the fish mature and can handle changes better.

Hope this helps.

 

[Joolz]

Really appreciate the advice - I was told to use the main tank aquarium water for the water changes from a local fish shop assistant stating it was where they originated so the bacteria from there would be good for them. I will try the baby shrimp - also I have noticed the other fish I thought I had lost trying to swim up but really struggling and just resting on the gravel so don’t know if it will survive. I have been doing the small water changes every other day and just using a turkey baster to get any gunge out. Thought the danios were meant to be quite hardy fish and easy to look after - spending more time with my fish than I am my dogs at the moment [emoji2]

 

[Jacky12]

I’m learning lots from you, Andy. Thanks

 

[Andy Sager]

Really appreciate the advice - I was told to use the main tank aquarium water for the water changes from a local fish shop assistant stating it was where they originated so the bacteria from there would be good for them. I will try the baby shrimp - also I have noticed the other fish I thought I had lost trying to swim up but really struggling and just resting on the gravel so don’t know if it will survive. I have been doing the small water changes every other day and just using a turkey baster to get any gunge out. Thought the danios were meant to be quite hardy fish and easy to look after - spending more time with my fish than I am my dogs at the moment [emoji2]

Raising fish fry ( a.k.a. baby fish) is a job so spending time is not unusual. It's also full of ups and downs. Successes and failures.
Zebra Danios are actually very hardy but very sensitive to bad water. This is why they were used to create glo-fish so that public water systems could detect pollution in their systems. They were not created to be aquarium fish although that is what happened with them and the other GLO species once the technology was perfected.

Just so you know, the beneficial bacteria in the tank is found more in areas with higher oxygen content than free floating in the water column. This is why you find higher populations of bacteria in filters and on substrate that has good water flow over or through it. The sales person was incorrect in using that as their reasoning for using the main tank's water. Keep up your current schedule and use new clean water, similar in chemistry and temperature to the fry tank's water for your water changes.

At 2 months old, if the fish is unable to swim, the chances of it ever swimming is minimal at best. It's obviously finding food to be able to survive this long so if you want to try, see if adding the baby brine shrimp does anything for it. Just don't get your hopes up.

Lastly, obviously your tank is functioning well enough for the Zebras to breed so if you find raising the fry too much of a hassle, just let whatever happens to the fry happen. The eggs alone are a good fish food for your other fish ( and the parents as well) as are the fry. You may be surprised and if there is enough cover in the tank, you may have some actually survive to adulthood.

 

[Andy Sager]

I’m learning lots from you, Andy. Thanks

LOL You don't spend 50 years breeding fish without learning a thing or two. Glad to be helping.

 

[Colin_T]

Hi and welcome to the forum

Can you post pictures of the fish and white cobweb stuff?

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With baby fish in a small tank, the water quality (ammonia, nitrite, nitrate) can go off very quickly without a filter. This is due to the amount and types of food being added to feed the fish. It's a good idea to do a big (50-75%) water change every day on the fry tanks. I use water from an established plant tank so it is free of chlorine and other harmful chemicals. You can also use water from the parent fish's tank. The reason for using water from an established tank is primarily due to the water having the same chemistry as the rearing tank and has nothing to do with beneficial bacteria, which as Andy mentioned, live primarily on hard surfaces and not in the water column.

Once the babies are over a month old, you can start using dechlorinated tap water for water changes, or keep using water from the main display tank.

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You need some aeration in the tank to circulate the water and help keep oxygen levels up. If there is too much aeration, you can buy T-pieces and taps to go in the airline and bleed some of the extra air off. Most air pumps can also be adjusted to reduce the amount of air they pump. There is either a high/ low switch on the pump or you can loosen the screw that holds the air chamber in the pump. The screw is small and located on the side of the pump. Not all pumps have a screw for the air chamber but most do. Loosening the screw allows air to leak out of the air chamber and less air is pumped into the tank.