Baby Pyjama Cardinalfish


New member
Hey guys! I thought I'd write this as an informal guide to raising baby pyjamas. This is the third batch my pyjamas have had (first batch died of starvation, and I didn't bother trying to raise the second batch since we didn't have enough rotifers yet). The first batch died because my dad wouldn't let us culture rotifers until our fish actually had eggs, and as we all know it's too late by that point. Anyways, the rotifers have been set up since February 8 or so (it's a mix of type S and L), so hopefully we have enough rotifers this time! We also started up a copepod farm as well, and two phytoplankton jugs last week.

Our big male's been taking on new batches too quickly. He needs to rest between batches, but unfortunately he only waits a few days after carrying the eggs to term before taking on a new batch.

Anyways, the infants seem to be doing well. I collected 2 eggs that the male dropped on Thursday. The one infant hatched that night, so I put him in the nursery, but he died during the night. His tummy was full of food when I found his corpse, so I think he must've just been defective. His brother (I'm just going to refer to them all as being male) hatched sometime after 2 am, and was swimming around like a champ in the bag I had his egg in in the sump. I released him into the nursery tank (it's a 5g that we filled with water from one of the rotifer buckets and a bunch of live phyto so the water's nice and green, Seachem Prime, a Cobalt Neotherm set to 76°F, and a very gentle airstone, along with the light I use when painting miniatures), and he immediately swam over to the heater and started nibbling on it (I think he might've been eating biofilm).

Later that evening the male finally started releasing eggs (it was day 8 or 9 of incubation), half a dozen at a time. To collected eggs and fry, I turn off all the pumps, gyres, and other various blowy and sucky things, increase the brightness in the tank so I can see any eggs and fry clearly, and I use a target feeding stick with the tip removed. I use a regular target feeding stick (the kind with a clear tube, blue tip, and blue squeezy bulb) to collect eggs and infants, as it's the easiest, most accurate way to collect them.

Anyways, the male's a real pain in the butt, because he knows I'm after him and his eggs, so he's constantly trying to hide in the rock work, which means I have to be on my feet almost the entire time, following him back and forth, waiting for him to drop some eggs when he "gargles" them in his mouth.

I ended up collecting 20 eggs, plus an infant. I put the twenty eggs in a Ziplock baggie that I clipped to the side of the sump, and I put the infant in a separate baggie. I waited 3 hours before adding the infant to the nursery to be with his brother. I reasoned that the first infant might've died during the night because he might not have been old enough to swim properly before being dumped in the nursery tank filled with biofilm, and that he might've got stuck to the biofilm before he could learn to swim properly. Either way, it doesn't hurt to wait until they're swimming somewhat proficiently with a horizontal posture before adding them to the nursery.

It should be noted that pyjama cardinalfish fry/eggs start being released in a significant number around days 7"“9, although inexperienced males may start inadvertently dropping the eggs while tumbling them in their mouths around days 5 and 6 of incubation. Not sure how many eggs they actually carry, but I'd say there's anywhere from 40"“100 eggs in a batch.

Hatchlings are roughly the equivalent of 3"“5 day old bettas in terms of development. Hatchlings infants have distinct eyes, a distinct swim bladder, and a very small yolk sac that can only sustain them for maybe 12 hours or so after hatching, so you'll want to get them in a nursery tank that's dense with rotifers, fairly cloudy green with live phytoplankton, and maybe copepods for them to munch on once they're bigger.

They aren't nearly as developed as Banggai fry, and MUST be fed a constant supply of rotifers, and according to what few reports I've read on rearing pyjama fry, their tank must be kept noticeably green with phytoplankton to gutload the rotifers with. Some websites say baby pyjamas can be fed baby brine shrimp immediately after hatching, but this is a bunch of nonsense, seeing as BBS are about half the size of their head. Cleaner shrimp larvae are able to eat BBS, but this is because they have legs they can use to catch and hold large food items with. From what I've read, you can start introducing live BBS to their diet from days 10"“12, but no sooner. Up until then, they need to eat rotifers and copepod larvae.

Anyways, after 3 hours I added the baby pyjama to the nursery to be with his brother. His brother noticed him immediately. By this point the "older" baby had been out of his egg for more than 12 hours, yet unlike the infants from the first batch, he was still alert, was swimming really well, and appeared to have a good amount of food in his tummy. They're really freaking tiny (maybe 1mm or 1.5mm in size?), so I couldn't tell if the amount of food in his belly got smaller. I checked on them until 2 am to monitor their energy levels and the amount of food in their tummies.

Today I checked on them at noon, and both babies were still alive, swimming around really well, and had full bellies. I did a 50% water change with water from one of the rotifer buckets, added more phytoplankton, and added more Seachem Prime. After that, I checked on the eggs, and 18 of the 20 had hatched, and they seemed alert and were swimming around, so I put the two eggs in a different bag, then moved each baby from the bag to the nursery using the target feeder, counting each one. They were all swimming relatively well, with some better at swimming than others. Some of them like grabbing food off of the bottom of the tank, while others tend to just feed from the water column.

The "new" infants are swimming very well now. Unfortunately this evening I noticed one of the babies laying on the bottom of the tank, and he was dead a couple of hours later. I think he just wasn't as strong as the others. I'm still waiting on the other two eggs to hatch. The eggs still look nice and healthy.

I'm confident they have enough food this time around, although I need to order Otohime A1 and B1 for when I wean them onto commercially prepared food.


New member
Most of the infants are still alive. I'm consistently counting 14 babies, and I couldn't find any corpses. I saw one infant die tonight. He laid down on his side one the bottom of the tank, and jerked around a bit every now and then over the course of 10 minutes before dying and turning white. Not sure why he died.

I added phyto a couple of times today, as I think the rotifers in the nursery are gobbling them all up.

The infants seem to feed almost exclusively on the biofilm on the bottom of the tank. It's not a graceful grazing like you see with tangs or whatever, but instead more like sharks tearing apart flesh.

The infants are developing nicely, and their mouths are now a distinct pyjama cardinalfish shape, and I can actually see their mouths hanging open.

A copepod swam past one of the infants, and he continuously turned in order to watch it swim away.

I notice the infants spend the evening hanging out in the bottom third of the tank, grazing before bed. It's kind of odd since I leave the light on for them 24/7 so they can see since I don't know how well they can see in the dark. Last night they started falling asleep around 11, and had naps while letting the gentle current float them around the tank. I turn their light down a bit dimmer at night to sort of replicate a day and night cycle, although the light is still quite bright at night. I probably won't turn it any dimmer than it already is at night until they're a couple of weeks old.


New member
Congratz on the babies. Have you been checking the ammonia? how often are you changing the water. Dead food tend to foul the water quickly. I use live bbs.