You have many years before worrying about rehoming, getting a larger tank, etc. Females tend to grow larger, sometimes gravid with eggs, fatter. Males typically stay smaller, but other then girth and dominance, sexing is uncertain.
I have seen smaller suspected males under 8", and 15 yrs old.
I once had a group of I think 13 in a 125, by themselves as a single species tank. I grew them out over several years then eventually parted them out to friends with much larger tanks. I currently have a group of 4 in a comm tank. As a single species you will see behaviour that you will never witness in a comm tank.
I have never owned a weak loach, but I have always bought them at larger sizes when I know they have survived export, are eating, and have no internal issues. As stated, many wild caught CL's are imported with worms, etc. There are a few active domestic breeding programs (with hormones) but the vast majority of CL's being sold are collected from the wild in either Borneo or Sumatra. I have a sticky on how to tell the two strains apart in the loaches sub forum.
https://www.monsterfishkeepers.com/forums/threads/clown-loaches-kalimantan-vs-sumatra.491976/
I highly recommend feeding 1mm NLS Hex Shield to any newly purchased or sickly looking CL's, and then deworming with Levamisole.
Good luck
I have seen smaller suspected males under 8", and 15 yrs old.
I once had a group of I think 13 in a 125, by themselves as a single species tank. I grew them out over several years then eventually parted them out to friends with much larger tanks. I currently have a group of 4 in a comm tank. As a single species you will see behaviour that you will never witness in a comm tank.
I have never owned a weak loach, but I have always bought them at larger sizes when I know they have survived export, are eating, and have no internal issues. As stated, many wild caught CL's are imported with worms, etc. There are a few active domestic breeding programs (with hormones) but the vast majority of CL's being sold are collected from the wild in either Borneo or Sumatra. I have a sticky on how to tell the two strains apart in the loaches sub forum.
https://www.monsterfishkeepers.com/forums/threads/clown-loaches-kalimantan-vs-sumatra.491976/
I highly recommend feeding 1mm NLS Hex Shield to any newly purchased or sickly looking CL's, and then deworming with Levamisole.
Good luck