Best Way To Handle A Fish Outside Of The Water For Id?

[Dave Legacy]

Hey everyone,

I guess about 2 weeks ago we had a discussion about identifying the different species of archerfish. I though I had Toxotes Jaculatrix and then was brought to think that I actually had Toxotes Microlepis. My Specific Gravity was about 1.008SG and the fish didn't seem all that happy about it, not too stressed though. Over the last 2 weeks I have brought it down to 1.004SG and today two of them look pretty stressed out. Charcoal gray in color and pulling thier fins in pretty close to their bodies rather than faning out.

I was looking at a few fish books at the bookstore today and both photos I found of Toxotes Jaculatrix looked exactly like my fish and had 4 dorsal spines. I believe that Microlepis has 5 dorsal spines, correct? I need to know exactly what species of archer I have so I can put them in the proper conditions before they decide they've had enough and die on me. I think I need to count the dorsal spines but to do this I need to take them out of the water.

What is the best way to do this? I have a good net. I really don't want to stress them to the point of death.

Thanks,
Dave

 

[Dave Legacy]

Here's a pic from Wikpedia.com labelled Toxotes Jaculatrix:

Now here's a few pics of mine, the best I can get for now:

Accidental flash, probably blind now!

This is one of them in the holding tank at the LFS I bought them from. As you can see I've been documenting them from day 1.

My entire shoal.

You can kinda make out the number of dorsal spines in these, 4, that doesn't help much right?

Do these pics help? Maybe I can avoid taking them out of the water or handling them.

 

[nmonks]

Hi David,

I don't know how familiar you are with Fishbase, but it is particularly useful for identifying brackish water fish. In this case, you go to the front page, go to the "Information by Family" segment, pull down the menu there and choose "Toxotidae", and then click the "Family info." radio button. That takes you to the Toxotidae family page.

http/filaman.ifm-geomar.de/Summary/Famil...mary.cfm?ID=337

Once you've read up about the family there, what you do is click on the link "Show species" at the bottom left. This takes you to a listing of species.

http/filaman.ifm-geomar.de/identificatio...e=337&areacode=

As you can see, there are seven known species of archer. You want to narrow it down. There are multiple ways to do this. One way is to select the region the fish has come from. At the top you will see an option entitled "Select Ocean (marine/brackish) or Continent (freshwater)". Pull down this menu, and select the place the fish has come from. In this case, you would choose "Asia - Inland waters". You will see the list of archerfish species has been reduced to five species. You can then crop the list further by choosing a country using the "Select Country" option. In this case, it will likely be Indonesia or Thailand, simply because that's where most tropical fish like these come from. Choose either, press "redo", and you'll see the list reduced to four.

The next thing you can do is reduce the list further using dorsal and anal fin spine counts. Your fish have 4 dorsal spines. Type that into the box by "dorsal", and press "redo".

Unfortunately, this doesn't seem to help much, as both Toxotes jaculatrix and Toxotes microlepis are reported to have 4 dorsal spines, though Toxotes microlepis can have 5 spines as well. This conflicts with Schaefer's diagnosis of these species that I reported earlier on, where 4 spines were said to distinguish Toxotes jaculatrix alone.

In other words:

Toxotes chatareus -- always 5 dorsal spines
Toxotes jaculatrix -- always 4 dorsal spines
Toxotes microlepis -- 4 or 5 dorsal spines.

The question is how often Toxotes microlepis has 4 or 5 spines. If it mostly has 5 spines, then Schaefer's diagnosis is reasonably reliable. But if it is 50:50, some 5 spines, some 4 spines, then things get messy. Both the pictures of Toxotes microlepis at Fishbase have 5 spines, but that's a sample of 2 fish, one of which is a drawing, so I don't place much value in this observation.

Here's something that might be more useful. If you look at the photographs, Toxotes microlepis definitely has smaller scales and these form long, curving rows along the flanks. If you look on the pictures below, notice how on Toxotes microlepis the rows of scales behind the pectoral fin curve up and then down. In contrast, those on Toxotes jaculatrix appear in quite steady rows, and the scales look much more robust. Again, this is a small sample of fish and may not mean anything, but if the Latin name of Toxotes microlepis is anything to go by (the second bit means "small scale"), then small scales are the giveaway for this fish. Can you post a close up picture?

Anyway, the moral of this story is that identifying fish is very difficult, and that scientific authorities often contradict one another!

One thing: SG 1.005 should be fine for young archers. I've kept them in hard freshwater without problems for months, and longer at SG 1.005. Yes, Toxotes jaculatrix probably likes a higher salinity, but it isn't nearly so sensitive to this as, say, monos and scats. Here's the thing: is it the same fish that are looking grey and stressed out? If so, I'd put my money on intraspecific aggression. I have yet to see a group of archers work out in a small tank. They seem to have a very strong hierarchical behaviour. This may be more of a problem if you keep them in pairs or triplets than in larger schools, but either way, I'd have a look and see how the fish are behaving towards one another before worrying about the water chemistry too much. Incidentally, do check things like pH and nitrites. Even if the salinity is sub-optimal, you can make life a lot easier by maintaining a high pH and zero nitrites.

Cheers,

Neale

Toxotes microlepis

Toxotes jaculatrix

 

[Dave Legacy]

Neale,

The problem I've been running into with fishbase is like you stated, only the 2 pictures of Microlepis and one is a drawing. I guess I could check all of my fish and if any of them have 5 dorsal spines then it would probably be safe to say they're T. Microlepis. Now does the small-scale refer to the overal size of the fish or the size of thier scales? In comparison to T. Jaculatrix they are much smaller scale. Do we know the exact meaning of that name?

Right now they're in about 1.004SG and they seem to be ok. There is some aggression between them. One of my smaller archers is a bully if anyone comes into her territory during feeding time unless there is enough food for everyone. They have recently seemed to split into different territories although I still find them schooling together quite frequently so it's really hard to tell what is going on.

It's very possible that they need more room. I might need to accellerate my new tank project. The new one will be 36x36x31 which should hopefully give a large enough footprint for them to feel comfortable and relaxed. I will try to a detailed close up photo of them so we can do further observing. I could also try to video take them during feeding time when they fan out their fins to see if I could freeze the frame and count all their dorsal spines without handling them.