Well first you have the upper jaws which their jaw protrudes or is equal in length to their lower jaw.
1) Senegal- The senegal is the most "plain" looking bichir of them all will basically no patterns other than their base color. Their head shape (as I've noticed between CB and WC) can vary. WCs tend to have a slimmer more "natural" looking head, while CB have a more rounded head just fitting everything (eyes, nostrils etc..,).
2) Ornate- Ornate is probably the easiest one to distinguish from the others from it's distinct patterning.
3) Delhezi- Delhezi are often confused with endlicheri because of their stripped patterning. An easy way to tell the difference is by the jaws. The delhezi is an upper and endli is a lower. Another way is the patterns. This isn't the case all the time, but for most times delhezi will have a lot more stripes than endlicheri. Another way (again not always, but from most) is that the delhezi patterning is usually vertical where as the endlicheri patterning is more of a diagonal type patterning. The delhezi will usually have a grayish (many shades of gray depending on substrate). Another key distinctive trait is delhezi have a "cross-type" marking on their head. This marking appears to be on many dels, but not all of them.
4) Palmas Palmas- All of the palmas' cause confusion just because of the name, but distinguishing them is usually pretty easy for the most part. Sometimes however it is rather difficult to distinguish buettikoferi and palmas palmas. Palmas Palmas usually have more distinct bars for patterning and have almost a "camoflouge" type base color. They can have varying base colors and pattern sizes/shapes etc.., so it is hard to create a guide for this one. However the palmas palmas stripes will be somewhat like the delhezi's patterns, but usually a little bit bolder and the palmas palmas base color will be more of a brownish.
5) Palmas buettikoferi- The buettikoferi will usually be a little lighter in tone than the palmas palmas and their patterns won't be as defined. Their patterns will be much slimmer sometimes not even really forming any real stripping and rather looking more like small scattered black stripes. They are also known for getting a decent amount of yellow on their stomach and extending to their sides and sometimes even to the tail/pectoral fins, and under the head.
6) Palmas Polli- The Polli is easily the easiest of the palmas' to ID as it has more of a undefined pattern. It usually gets more of a blueish green base on dark substrate, or on light substrate gets a marble type tone. It's head shape somewhat resembles the senegal. Palmas polli are also known to be very active to. A distinct characteristic is the amount of dorsal finlets it has. It has only 5-7 finlets and they may not start until halfway down or even later down it's back.
7) Teugelsi- Teugelsi are usually pretty easy to ID because of their reddish type appearance. Most times Teugelsi (WC or CB) will have some red (even though it may be more apparent in some individuals than others). Teugelsi also seem to have some sort of black patterning. I have seen all different kinds from stripes to almost all of the body being black to almost none of it being black. So the black aspect may vary between individuals. Teugelsi are also known to look very elongated when they grow larger.
8) Retropinnis- Retros are often mistaken for palmas polli because of their patterning sometimes. Retros can most times be ID from the speckles surrounding their eyes. This isn't a surefire way, but this way is similar to like what the del has with it's "cross". Retros also tend to be more green/gray and have more of a spotted pattern in some cases. They do also get some black, but nothing compared to what some of the other species get. It also can get a mix of spots and stripes towards the end of it's body.
9) Mokelembembe- The moke is a unique bichir in and of it self. It was originally named retropinnis, but was changed to mokelembembe so there is still some confusion with some sellers that sell them as retropinnis. The moke seems to be one of the shyest bichirs. It's patterns resemble almost large elongated bars. However mokes usually just keep a dark brownish/black base with slightly darker patterns. Another way to ID them is their dorsal finlets. Their dorsal finlets like the palmas polli start farther down their backs than most species and may only have 6-8.
10) Weeksii- The weeksii is known for it's large head. It also have stripped patters like a delhezi. However the head on a weeksii is very unique in the shape and size. Weeksii are also somewhat shy.
Now onto Lower Jaws- Lowers Jaws are polypterus with jaws equal to or that protrude past their upper jaws.
1) Endlicheri- The endlicheri is often mistaken for delhezi (and vice versa), but endlis have much flatter head and their patterns are much wider then delhezi's. However CB endlis now seems to have horrible head shape with eyes that appear to resemble "frog eyes" as they are almost squished onto the head.
2) Lapradei- Laps have more elongated heads than endlis and their patterns are more horizontal running through their tail, however the variants seems to all have their different patterns and special patterning to themselves, but thats for another discussion.
3) Congicus- Congicus are sometimes mislabeled as endlicheri, but are not in fact endlicheri. The congicus head resembles that of an endlicheri, but the patterning is not as wide and tends to have more stripes that are skinnier.
4) Angsorii- Angsorii have almost a lap type pattern, but there is a blank line that runs down their tail (like the lap). It is almost as if someone took a laps patterns and an eraser and erased a single line. The head shape is unique to. It is wide like an endlicheri, but still different. (I personally haven't kept angosrii so I can't speak of any firsthand differences.... yet)
5) PBB- To me Bichir Bichir has lap type patterns, but much bolder. They also have similar head shape, but they appear to have way more patterning on their head than laps do.
Again this is just what I have observed in my tank and the differences between the different species. I will say though nothing makes more of a difference than practice. Seems like an odd thing to practice, but the more you become accustomed to seeing the different species the more you can tell the differences. It takes time so if you can't ID everything at first don't sweat it just keep learning.
Another thing is the palmas palmas and delhezi. The palmas palmas vary in patterning so much that it may be hard at first. I have 4 different specimens and all 4 have different patterns. Another is the delhezi. There are also what is known as "royal tiger" delhezi which are basically just delhezi with exceptional patterning so they usually won't have vertical stripping, but rather have black stripes or patterns every where.
