I am currently breeding Banggai Cardinalfish
Currently I have 2 breeding pairs, one pair is actually from the first pair, which would make them F2 generation.
Pairing:
The hardest part is obtaining a good pair. First off, as many of you know, they are difficult to sex. I have found they aren't really sexable until about 9-10 months of age when they become sexually mature. When it comes to determining sex, I first look at behavior or physical features. Don't look at size or dorsal fins, they are misleading. My pairs are opposites in this regard; the oldest pair I initially thought the male was female and vice-versa. The female of the oldest pair is larger, and also a longer dorsal fin (which is why I thought it was a male) than the male. The younger pair is more traditional, with male being bigger and larger features.
I look at behavior first. If looking to obtain a good pair, buy a group of about 6. The most dominant ones will pair off first and start pushing the group away, and then net them out. It is very hard to have one fish, and guess at the sex, and just buy another single fish. It usually doesn't turn out well. Even the group of 6 has a little "shoving" to pair off, one-on-one is usually too much for the new arrival. By having a group, you distribute the "shoving" among 6 until a pair is formed, then they almost always claim half the tank and push the remaining to the other side, then you have a pair and no fish died. You should then move the others out; I often give them away to let people make pairs, as you can make your money back with many babies.
Secondly, after the pair is established, it becomes very easy to know which is male and which is female. The jawline is the easiest physical feature for me to use. Males have "rounder" jawline, while the female is more straight. My females also get bright reddish bellies when they are ready to spawn.
Another reason I like group pairing is that you are more likely to get the strongest pair. One-on-one pairing you can end up with a weak pair or a weak female, or worse a weak male. The biggest female will choose the largest male. This is sexual selection. Larger females produce more eggs and need a large male to hold them all. A large male also indicate health which excites the female. It is very odd that the parental roles of these fish are totally reversed. The male holds the eggs and is very evasive, as he has no real defense, while the female is very assertive and protective of the pairs area.
Once you have established a pair, getting them to spawn is easy! Just keep them "happy." They like lower flow calm tanks. My pairs are both alone (OK one has an ancient mandarin goby). I have urchins, although you don't need them it's just cool to watch the natural behavior and is also a good place to catch the babies. Plants are also good. Keep them WELL fed. The female needs GOOD foods to make good eggs and the male needs power fed as he will be holding eggs in his mouth (and not eating) upon spawning.
Spawning:
I have seen the actual event, very cool. I didn't see the first few spawns, but after becoming comfortable, they do it openly now haha. It starts with the female courting the male. She will follow him around relentlessly. He will play it cool staying still. She slowly swims up to his side almost touching him, and starts shaking/vibrating. Then, she slowly moves behind him (always behind for some reason) to the other side and shakes/vibrates again. She will do this 10-20 times. This is to tell the male "get ready." She will lay approx 40 or so eggs, give or take 5-10 based on her size (I have stripped his eggs to count them, he took them right back). They are pinkish-orange, and kind-of hang from a cord from her. The male will fertilize them very quickly and gobble them right up.
Rearing:
This is when obtaining a "good" pair is essential. Don't be surprised if the male eats the eggs a few days or a week after the first spawn. This simply means the female rushed the male and he wasn't adequately fed beforehand. It takes the female about 4-6 weeks to spawn again, use that time to power feed the pair. A good male is priceless as he does all the work (man things are backwards haha). A successful release of viable young will require him to hold the eggs (while not eating) for 23-29 days. I have had at least 8 batches from the oldest pair in a little over a year which means he has only eaten like half of the year, month-on, month-off...truly amazing.
During the 23-29 days the female still eats as usual, I feed normally to allow her to make eggs, but don't power-feed as it will rush her and throw the timing off. She will guard him fiercely. His first instinct is to run. He will yawn and move the eggs around. As time approaches the 23 day mark, his mouth really starts to swell, and yawning increases. His mouth enlarges while his stomach shrinks, the whole time showing no interest in food.
Release:
Release almost always happens at night before dawn. This allows the babies a chance to hide and acclimate. I usually net the male out and place him in a separate nursery tank at around 23 days. My nursery tank is a 15 gallon attached to the breeding setup, which keeps the water identical (bare bottom with fake plants and fake urchins). You must be careful how you net him. Don't chase him too much, if he panics, he can suffocate which will cause him to eat or prematurely release his babies. I also move him from the net to a cup underwater. I never take him out of water with babies.
He usually releases 18-25 babies. I have counted 45+ eggs when they were stripped from him. I think he is snacking on some (probable), or some die (probable), or some cannibalistic activity which I doubt because there is none after release. The babies are tiny replicas of their parents, pretty much translucent where the silver is and black where the black is with no spots. Some have pinkish yolk remaining depending on release age.
I then catch the male, though there is no real rush with a good male. Even after not eating for a month a good male still won't eat his babies even though he easily could. I then either put him back directly with the female or separate them with a clear divider in the same tank. The decision is based on how many batches he has done lately and how fast. If it's his first one I would probably put him back, if it's his 5th, I give him a break. The female will rush him causing him to eat the eggs. I separate them with a clear divider (to allow for pair bonding), and I power feed the male to get him to proper strength so he can successfully hold another batch (NOTHING beats a good male, I have tried to strip eggs and rear them in a tumbler and have had poor results at best)
Feeding the babies:
You should have had baby brine shrimp (BBS for short) hatching and fresh since you put the male into the nursery. You must have live baby brine hatched BEFORE the babies are released. You DO NOT want them hatched and then have to wait 15-24 hrs to hatch BBS. You want to have fresh LIVE BBS going at all times, multiple cultures of different ages. It sounds daunting but it is really not. I have the classic upside down 2-liters and they are in my sump to keep temp. I keep 3, hatching, hatched, and enriched at all times when babies are due or around. All it takes are 3 2-liters, an air pump, ridged airline, and put them in your sump.
Feed at least 3 times daily, better being 5. Newly hatched BBS is best. After about 4 hrs BBS have lost most of their yolk sacs (main nutrition) and will have to be enriched. I use selcon, and spirulina zoe to enrich. This is MANDATORY or you will end up with babies that have SUDDEN FRIGHT SYNDROME (SFS). This is when babies aren't fed enough fatty acids (selcon/zoe) and they suffer from SFS which is usually fatal. What it does is causes the babies to use essential fatty acids that are used for nerve building/function just to sustain life and they suffer from nerve damage. Basically any large stimulus (feeding, lights going on, a net) causes them to literally short circuit.
Once they are feeding well and growing, usually a month or so later, you can get them onto frozen foods like baby brine or adult brine and mysis, but I still enrich everything until they are close full size. I haven't however gotten any of mine, babies or parents, to eat flake or pellet. The only prepared foods they will eat are Instant Ocean Gel foods, and the semi-moist mysis in the can. I don't have the heart to starve them to see if they will convert.
They are usually sell-able when their main body (minus fins) is dime-nickel size (maybe 3-4 months?), and they must be on at least frozen foods. I have found many local people; independent, wholesale, and retail like, and prefer, to buy from local breeders.
In summary I would say this, obtaining a pair is hard, spawning and getting babies is easy, raising babies is hard, and time consuming, and not a money-maker, but is very rewarding to see happen start to finish. Come on these fish need it!
Please ask any questions!
Few weeks old vs. one day old
Gravid female
Few days old with pink bellies
F2 Female
Microscope Shot of enriched Baby Brine Shrimp
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