Assuming you have an appropriate filter setup and do regular water changes, this is probably fine. My caveat is that [AqAdvisor][1] treats the loaches as potentially reaching 10", which would be a bit large. [Fishbase][2] says the largest on record was about 6" though; I'm not sure which site has the better handle on that species. (Note that I picked a fairly hefty filter for the AqAdvisor setup, and assumed you have a rectangular tank.)

Bioload isn't one single thing to measure. It's an overall concept that deals with all the basic components of life needed by the organisms within your tank, all the byproducts they create, and the natural cycles they form. Bioload is basically a way of thinking about how open (or unbalanced) these cycles are within the tank: the heavier a bioload, the more a cycle is forced open by something being consumed or created faster than the system can respond to it. We take for granted that some of them, like the food/nutrient cycle, are completely open and need constant intervention.

Often people say 'bioload' as a shorthand for nitrogen wastes: ammonia (NH3), nitrites (NO2), and nitrites (NO3). You should be testing those weekly with a reliable test kit (I like API's), or more often if your system shows signs of being unstable. Ammonia and nitrites are toxic to fish in any amount; some nitrates can be tolerated but they should be kept under say 20ppm or so. 

In this sense, a bioload is too high when those ammonia and nitrites are being produced faster than the biofilter can reduce them to nitrates. It's hard to say "if you have *x* fish you need *y* biological filtration" because each species of fish and each model filter is different. But generally it's hard to provide too much biological filtration, so get the largest filter you can. Plants and water changes will help keep nitrates down, and these are really the only way to 'close' this cycle.

Oxygen is another critical cycle. The gas exchange that oxygenates the tank happens at the surface of the water, and you can run into problems if you don't have a lot of water movement to mix the surface layer back down to the middle or bottom of the tank. Plants will help with this too, but you'll still need water motion to get oxygenated water to the entire tank. Odds are you won't have a way to measure how much dissolved oxygen your water has, and as long as your water is moving top-to-bottom and side-to-side you'll probably have enough. You can read more about DO levels [at the EPA][3] if you're interested.

There are other cycles as well, like phosphorous and carbon, that you don't need to worry quite so much about. They tend to be at such small scales that normal maintenance easily keeps them closed. These can be more important in heavily planted tanks though.


  [1]: http://www.aqadvisor.com/AqAdvisor.php?AquTankName=&AquListBoxTank=Choose&AquTankLength=36&AquTankDepth=18&AquTankHeight=21&AquListBoxFilter=Eheim%202217&AquTextFilterRate=160%20&AquListBoxFilter2=Choose&AquTextFilterRate2=N/A%20&AquFilterString=loach&AquListBoxChooser=Yoyo%20Loach%20%28Botia%20almorhae%29&AquTextBoxQuantity=5&FormSubmit=Add%20%3E&AquTextBoxRemoveQuantity=&AlreadySelected=200909300005:6::,200909300131:3::,200909300029:3::,200909300207:3::&FilterMode=Display%20all%20species&AqTempUnit=C&AqVolUnit=gUS&AqLengthUnit=inch&AqSortType=cname&FilterQuantity=2&AqJuvMode=&AqSpeciesWindowSize=short&AqSearchMode=simple
  [2]: http://fishbase.org/summary/Botia-almorhae.html
  [3]: http://water.epa.gov/type/rsl/monitoring/vms52.cfm