I see people asking is their fish big enough to spawn. Age determines maturity... Size doesn't matter. It seems weird(to me) to think that a stunted fish would not develope the same organs that a fish grown out at the right rate would. The only reason smaller fish don't seem to spawn as quick is because they don't feel dominant. If they are in a tank to themselves then everything is a GO! I've had smaller "stunted" fish spawn and I just wanted to throw that out there. If you beg to differ... Chime in!
Size and Maturity...
- Thread starter crush329
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I completely agree. Age and not size determine sexual maturity. A large but not sexually mature fish wouldn't be able to spawn and vice versa
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I can tell you that from a marine biology (saltwater) standpoint, they both play a part. Most fish often have to reach a certain size before they become sexually mature and this requires a minimum time period (fish can only grow so fast). There are also fish that reach sexual maturity at a certain age, regardless of size, but these are more rare. Now take that with a grain of salt because I am talking about saltwater species. Freshwater is mostly the same as far as I can tell.
Having said that, size generally tends to determine sexual maturity with age being more of a secondary factor. For instance, there was a guy who posted here not too long ago that had a 3" female gold severum breeding with a 2" male green severum. Both sizes are very small to be breeding. Come to find out, he bought them from a guy who barely cared for them and they were stunted. The poster had them for 2+ months and they had not grown at all. So size is usually the determining factor of sexual maturity, but if that size is unobtainable, age will likely force sexual maturity into being.
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Having said that, size generally tends to determine sexual maturity with age being more of a secondary factor. For instance, there was a guy who posted here not too long ago that had a 3" female gold severum breeding with a 2" male green severum. Both sizes are very small to be breeding. Come to find out, he bought them from a guy who barely cared for them and they were stunted. The poster had them for 2+ months and they had not grown at all. So size is usually the determining factor of sexual maturity, but if that size is unobtainable, age will likely force sexual maturity into being.
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Here's another thread where I forgot to be more specific. I was actually talking about freshwater but I understand what your saying. I was given two clown fish that were at least 2 years of age but never spawned. Well when I got them 1 was bigger(female) and they began to spawn. With clowns fish the dominant male changes sex and they go from there. I don't think that happens with freshwater but I could be wrong. So I'm aware that saltwater is very different.
Now... Let's go back to freshwater. You said "size generally tends to determine sexual maturity with age being more of a secondary factor." That contradicts the whole severum example you gave. Basically meaning the new owner of the severums that finally got the two to spawn did not know the age and they were old enough and comfortable enough to have spawns with the new owner. So size was not a factor... Their age was. Some people just can't keep their water quality good enough for spawning while others have troubles keeping their pairs spawning. When small/stunted fish are returned to the store, the age is never known but that doesn't stop them from being able to spawn. Quick question though... So are you saying if one had a 5 year old 2" midas(or any common store bought cichlid), it wouldn't be able to spawn because it hasn't reached a mature size?
There are a wide variety of small saltwater species (less than 6-7" generally) that have the ability to change their gender based on their personal or social needs. I cannot think of any freshwater species that do this, but I am sure there are a few.
I may not have explained myself very clearly with the severum example. It boils down to this: In 95%+ of cases, freshwater species' sexual maturity is determined by size. But in rare cases where a fish cannot reach its sexually mature size (like if it is stunted), sexual maturity can be brought on by age. So lets say most severums are mature at around 6" that normally takes 8-9 months, but a 15 month old fish was stunted and has only reached 4". Sexual maturity may still take place before reaching the sexual maturity size. Was that explained any better?
So yes, size is the dominant factor in sexual maturity, but age can be a secondary factor as well. In some species, age is the dominant factor, but the species that use age as the primary determining factor in reaching sexual maturity are more rare.
A 5 year old, 2" Midas may very well be able to spawn. In some extreme cases (like an old fish that is very small for its species), the body simply doesn't have room to grow or enlarge reproductive organs.
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Ohh ok. Thank you for clearing that up for me. I totally agree with all of that.