Help, long-fin white mountain cloud minnow fry during tank cycle


I’m excited and also freaking out at the moment and really need some advice.
I’ve set up( added water in) my 120cm/4ft tank for mountain aquascape on 5th Oct. Although I was in the middle of the nitrogen cycle, I came across this long fin variety for sale by a fellow hobbyist 5 min drive away and I jumped at the opportunity. I have quite a few plants, Rotala, marsilea hirsuta, Anubias petite, Crypt, Several varieties of mosses...ets. I didn’t get an ammonia spike but nitrite and nitrate were present on 12th (Day 7), so I went for it. Now I’m going through nitrite spike for the last 5 days, and have been performed 50% water change daily. Today (Day17) the ammonia is .25, Nitrite is 2-4ppm and Nitrate 5-10ppm. pH 6.7-7. Water temp is 20-21 degrees AND found the fry on the aquarium front glass....20-30 of them.

My question is,
1. Should I do a water change or just dose with Prime? I do dose with Prime and add stability after WC. I have read the Prime dose detoxify 2ppm Nitrite per dose but have been doing WC due to clouding of water surface.
2. should I separate the fry or should I just leave them there and see what happens? I have Fluval 407 underneath on medium flow and the pre-filter sponge attachment haven't arrived yet. It is 200L 25-30% planted tank with only 4 adults.
3. Do I start feeding the fry after it start swimming?

I knew they were spawning but didn't think fry would appear given the minimal feeding, nitrogen cycle and the 50% WC! Also, I only have 4 minnows in there, two males and two female! I was going to super slowly stock the fish minimally (10? Just for bioload and watch them torpedo around the tank) and only keep longfin white cloud Mountain minnows for fish and slowly add Red cherry shrimp sometime next year after the tank has well and truly stabilized.
Love long finned white clouds ! Great fish .
Lucky finding a breeder..I suspect you are not in US??
If you have tank separate fry .If not see how it goes.
Yest to water changes and prime ..BOTH !!
Prime last 48 hours so depending on cycle you should be good with 50% daily and prime ..
Love long fin white clouds ..
Welcome !
  • Thread Starter

Thanks! I will do the WC as per normal with a net!
I did toss about moving the fry into a bucket but now I see 50-70 on the glass alone. I’m going to leave them in and hope for the best. The parents are still spawning and I’m going to try keep the adult safe and finish the cycle rather than concentrating on raising the fry.


Yeah I’m in Sydney Australia. They are definitely not popular here either. I’ve never seen them at any of my LFS and I only know one online retailer who sells these guys. The guy I bought them off only had these guys for 3-4 months and he had tropical tank so I was initially worried about 24 degree water temp going straight down to 20 degrees but they are doing well. They colored up super quick and I believe 20 is closer to their optimal temp.

They are so beautiful already! Probably the fin length is not too much more than the normal variety but one male has clear yellow and red markings on the dorsal fin. Very long pect fins, too. I’m starting to see the female perform a fin display...its very interesting. I had my heart set on them with their beauty and ease of care but their character really took my heart! So happy to have them in the 4ft tank to see them torpedo right, left and center!

  • Thread Starter
Just an update,

Fish tank cycling is done!

I ended up taking 30 or so babies out into a separate container as I changed the water. Then Set up a 20L tank and breeding box in the main tank to compare fry growth and drop rate which seemed quite high initially.

Interesting note is as soon as many frys started swimming (1 week olds apparently) in the main tank, they ALL got eating (40 or so that remained). Since then, I have a female minnow who diligently check the glass and eat any fry in sight (free swimming or attached to glass). I am still getting a fry or two on the glass every few days....but if I don’t intervene, its gone within 30 min! I have a hungry hungry hippo

FYI...Let me know if anyone is interested in longfin mountain minnow fry growth updates. If so, I will make a thread. The babies are all F1 and I just got the parents so I have no idea what the genetics will be. Also on the interesting note, babies that are VERY black seem to drop very fast, as far as I know I lost all three (read somewhere it’s possibly the wild type?).

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