Baby rivulus not eating

[jon b]

Hi folks,
I am basically new to killies (but not fish-keeping) and hope you could help. Last week I got some Rivulus tenuis Papaloapam eggs. There is a steady stream of hatchlings but they seem uninterested in food and I have already lost some. I am feeding newy-hatched BBS (as suggested on other posts on this site, Baensch, plus the breeder) but the fish see uninterested as they do with Liquifry.
Would microworms be worth a try? I have a culture just coming up to harvesting.
The fish are in a 'clean' tub to allow food removal. Would a 'dirty' set up with lots of Java moss and floaters (with mucky roots from their unfiltered tubs on the windowsill) be better. (A couple of years ago we had some Aphyosemion that spawned without our knowledge but we stll got surving young that must have grown on the microlife on the tanks moss)
Is water critical for this species in your experience as the literature suggests not (pH is slightly alkaline but very soft)?
Many thanks

[RonWill]

Jon (?),
Sometimes despite our best intentions, a 'clean tub' is what fry don't need. If you had ever raised or hatched small fry, it doesn't take much to figure that infusoria, paramecium and all that microlife, is what fit into tiny mouths.

I am pro 'dirty tub' and don't forget to add some snails when the fry are free-swimming, as some of us are heavy-handed during feeding.

Also, check on your temps. IME, most killies tend to be lethargic when it gets too warm.

Good luck, welcome to the forum and do keep us updated.

[jon b]

Hi Ronnie,
Thanks for the advice. I have transferred the young to a net with lots of moss and floaters. I have also found that my tubs with plants have paramecium and rotifers so I am feeding water from these tubs into the tank wth the killies.
Temp was 26C so I've turned it down to 24C
Many thanks again, I will now cross my fingers and keep feeding as the babies are now very difficult to see
Jon

[RonWill]

Jon, 26°C is fine and I should have been more specific. By 'warm', that's in reference to our local weather in Singapore, which is between 29~32°C.

[mk_ultra]

what I like to do is throw a nice clump of Java moss into the tub with the fry. Provides hiding space and adds microlife. I also feed microworms as they are readily accepted into smaller mouths.

Good Luck!

[jon b]

Hi David,
Thanks for the tips, I'm also a great fan of java moss from breeding other types of fish and have put a big clump in with the babies. My microworm cultures are just maturing so I will start feeding tonight.
I have also noticied small worms (visible with a 20x eyepiece and only about 2 to 4x the length of paramecium) present in my (not good) infusoria mixtures from my unfiltered planted tubs. These are clearly aquatic and so could be a good source of food. Does anyone know what they might be and if they could be cultured?

[mk_ultra]

Here's another tip someone gave me...squeeze some juice from a well established sponge filter into the fry tub.

[jon b]

Hi everyone,
Thanks for all the tips and advice. I especially liked the filter idea as I always kick start new tanks with some 'sponge gunk' from an established tank but never thought of using it as food.
Although I have lost 5 fish I have 7 (probable number as lots of plants makes it difficult to be sure) that are growing and appear to be doing well. This includes 3 that I thought I had lost as they were in a plastic breeding trap and vanished into the main tank where despite not being specifically fed for 2-3 days they survived well (on filter gunk and infusoria around plants?) and are now taking grindal worms. The rest are in a net in the tank.

As well as the five I lost (at least 2 of which were just not taking food) I had some which hatched but then failed to develop further, not even absorbing their yolk sac. Is this common with Rivulus (or other killies) as I have not spotted it with other fish?

Thanks
Jon