Sexing silver dollars

[Dangerousdan]

True silver dollar Mylossoma duriventre are manic green eaters. I have 3 around 4 1/2" disc size and these things eat anything...and lots of it.
I also have 2 Schreitmullers Metynnis Metynnis hypsauchen around 5", these seem to appear more in LFS than the true silver dollars. No where near as distructive to the plants but still have a nibble.
The later have a red tinge in anal fin and lot smaller eyes. The former has red tinge on edge of caudal fin and dorsal fin. Also small black colouring on tip of dorsal.
Mine also have faint black spot shape just after the gill plate.
Dan

 

[CFC]

In European litterature the common name Silver dollar is given to Metynnis argenteus though tanks of silver dollars seen in stores can be either M.argenteus or M.hypsauchen. They can be told apart when adults as mature M.argenteus have black dots on their sides where as M.hypsauchen do not.

Mylossoma duriventre is a fairly rare import and is usually commonly called the Silver Mylossoma

 

[Dangerousdan]

In European litterature the common name Silver dollar is given to Metynnis argenteus though tanks of silver dollars seen in stores can be either M.argenteus or M.hypsauchen. They can be told apart when adults as mature M.argenteus have black dots on their sides where as M.hypsauchen do not.

Mylossoma duriventre is a fairly rare import and is usually commonly called the Silver Mylossoma

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Thanks for this interesting post CFC, spent few hours this moring trying to find out what species my dollars are
Will post some pics of mine later but in mean time heres some i found on net that look same as mine.

This is the fish i labelled as Mylossoma duriventre, which is what this pic was labelled as. I have 3 that look exactly same as this.

This is the fish i labelled as Metynnis hypsauchen, which is what this pic was labelled as too. I have 2 that look exactly same as this.

This is also what my 2 ref books have these fish labelled as. Whats the best site for getting accurate ID? Seems to be so many that have bad information

Picture credits:badmanstropicalfish.com

 

[CFC]

The top photo is a Metynnis argenteus, Mylossoma duriventre has a hook shaped dorsal fin and an anal fin which is thicker toward the tail than it is toward the anal vent. It also has a more pointed shaped mouth. Check out this link to see pics of a true M.duriventre http/kingsoftheaquarium.com/characins/mylassoma11-10.2.jpg

The bottom fish could be either a M.argenteus or M.hypsauchen as they are difficult to tell apart as juviniles.

 

[Dangerousdan]

The top photo is a Metynnis argenteus, Mylossoma duriventre has a hook shaped dorsal fin and an anal fin which is thicker toward the tail than it is toward the anal vent. It also has a more pointed shaped mouth. Check out this link to see pics of a true M.duriventre http/kingsoftheaquarium.com/characins/mylassoma11-10.2.jpg

The bottom fish could be either a M.argenteus or M.hypsauchen as they are difficult to tell apart as juviniles.

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Thanks
If the top fish is a Metynnis argenteus then the others definitly are not as the body shape is completely different. The 3 i have same as top pic have a kinda stretched look to there bodies where as the 2 i have same as bottom pic have a much rounder look to them and their eyes are much smaller. Oh and also a much brighter shiney silver colour.
Cheers for all information
Dan

Ill take soom pics when i get home from work.