ID : Sand or Common Goby?

[Andrew C]

Hello,

Pottering about on the Exe Estuary off Exmouth yesterday produced a few nice species but I remain unsure about a small fish. There were millions of small fish ranging from one to two inches long in the shallow sandy pools during low tide on the sand banks. Not much bigger than Common Prawns.

I believe these are either Sand or Common Gobies but could they possibly be too young to determine which?

Regards,
Andrew.

[Dogghound]

Looks good for Common Goby, this species is much more numerous in esturies too. Although Sand goby can be found in them too so not really a means of ID.

[Andrew C]

Thanks Dogghound. I also gleaned from the books that Common Goby was more prolific than Sand Goby in sandy estuaries.

Do you reckon these might be too young to be 100% sure of? Keep looking for bigger ones?

Cheers,
Andrew.

[Dogghound]

The lateral markings look developed enough, however without having the fish to hand makes checking small details like fins etc very hard. Has a female look to it, although sexual features often develop late. The only problem is both species could occupy the estuary so catching another may not reveal what this one is. The clincher with these is common goby lacks small papillae on the pelvic fin, also minor details in the way the gill is connected to the isthmus (chin area), which you cant see from a photo. If you get a really good image of the underside of its head it may be possible.

[Andrew C]

Thanks Dogghound. I clearly need to pay more attention next time I dabble in coastal species. I shall take my full range of books (four!) from now on and examine specimens fully.

I think I can easily catch another of these as there were hundreds.

Regards,
Andrew.