I have a couple updates, one that I meant to say something about last week, as well as something new. I'll start with the new tidbit. A new colony of bryozoans like the snowflake shaped ones that are growing on the right side glass appeared on the left side, almost in the same location. It appears that they prefer the darker areas of the tank. Either that, or I keep scraping them off when I clean the front glass.
The event that happened last week freaked me out, but I guess that I shouldn't have been all that surprised. Striped blennies are pretty fearless and tough characters in the tank. Even the smallest ones are brave and chase away both the gobies and the skilletfish (although both of the other species will chase them off too at times). But, I never expected this to happen:
It occurred in the 20g high tank. Yep, I lost a juvenile blenny due to skilletfish predation. This medium sized skilletfish ate my blenny!!!! I saw it happen. It wasn't a scavenging event. I couldn't believe it. All of these fish had full bellies. I mentioned last week that I gave all of the fish away from that tank, but this one little blenny was going to move to my 20g long tank. All he had to do was make it one more day.
Anyway, that is something to keep in mind when keeping skilletfish or similar clingfish. They have large mouths, and, although most of what you read about them says that they eat worms, amphipods, small crustaceans, etc., they will also eat fish, even small more aggressive ones.
Oh yeah, I forgot, there was more to the story. I actually trapped the skilletfish with the blenny in his mouth against the glass with my hand, so I could see if the blenny was still alive or not. The gills had already stopped moving by that time. I was going to try and free the blenny. But, since it was gone, I just let him eat it. This pic was taken after I released the skilletfish from being pinned against the glass. About 4 hours later, the blenny couldn't be seen and the skilletfish was fatter than fat....
Is your picture zoomed or cropped? I can't quite distinguish if the 'green' tail is what we are looking at, or the 'blue' head. I can make out the [orange] skilletfish well, but the oyster shell in the background muddles the distinction of the blenny being eaten. That's cool to watch.
LOL. Yeah, not a great pic for sure. But that is the head sticking out. The "V" shape is the 2 pelvic fins. It's sort of a ventral view. As I fed those fish soon afterwards, everyone ate but this skilletfish. By then, the blenny was just about down the hatch.
I have some updates on my 20g long. The Ulva is pretty much gone. I'm not sure that the parameters are right from growing macros in this tank (light, etc.), plus, I'm sure that the shrimp and crabs eat some of it. I probably won't add much until I get the main tank set up. I can't tell of the other macro is growing or not. There are some parts that seem to, and others I'm not so sure about. It looks good in the tank still, and provides good cover for the smaller fish, so I'm leaving it in there. The sea grasses have died off, so that experiment ends until I get the main tank set up. I have some cyanobacteria and some green hair algae areas on shells and sand where the most light hits that could be competing with the macros and seagrass for nutrients. Right now, I'm not too worried about this but would like to figure it out prior to setup of the main tank. We will see how that goes. I personally don't think it looks that bad as it still adds color, plus, the crabs and shrimp seem to eat it.
Both colonies of bryozoans are expanding across the tank glass on either end of my tank, in the darker areas. They look cool.
One thing that came in handy was the purchase of an automatic feeder to keep my fish fed while I was away on vacation. We couldn't find anyone reliable that new much about fishkeeping, so this was my solution. It worked out OK. The only issue that I anticipated was if the fish would actually adapt to and eat flake food or pellets, since, up until my trip, all they've eaten were live or frozen foods for the most part. My attempts at feeding them flakes were with mixed results. The gobies ate flakes with gusto. Some of the blennies ate the flakes, ingesting some or spitting out some, and other blennies ignored the flakes. The skilletfish ate flakes at times, but not often.
As far as pellets go, they were a little too big for most of my fish, and for the ones that tried to eat them, they spit them out at first and later kept attacking them until they were bite sized enough to eat them. The blennies broke them up and ate some, and then the gobies would follow behind and eat some of the fragments, while the skilletfish ignored the pellets altogether.
So, I made the decision to go with flakes in the auto feeder. I had no other choice.
After returning from my trip, I noticed that all of the fish will eat flakes now. Gobies still eat them with gusto, as do the blennies if they're hungry. If the blennies aren't hungry, they ingest them and sometimes eat some of the "flavors" while spitting out others. Skilletfish will eat flakes at times, but not that much.
The gobies and blennies all grew and are all fatter than fat. A couple of the gobies grew almost a 1/2" while we were gone (about 10 days), which I thought was amazing.
Also, I thought that I had only two crabs in the tank, but as it turns out, there are three of them. I've identified two of the crabs as the white-clawed mud crab, a.k.a. the Harris mud crab (Rhithropanopeus harrisii). I'm not sure of the third crab species as it looks different, but, I really haven't had a good look at them. Until now, the crabs have been hiding mostly. Recently, two of them come out during feeding time, and one of those is out foraging even while not feeding. In fact, last night, it was moving all over one of the oyster reef structures all the way to the water's surface.
From what I've read, they only grow to about an inch or so, and they aren't aggressive toward fish or shrimps. I'd bet they'd eat them if they could catch them, but, so far, I've seen blennies actually land on them and the crabs just move away. They raise their claws if fish near them, but so far, haven't tried to grab any fish. The shrimp seem to be good at avoiding them. I also read that these crabs feast on all types of snails. I don't have snails in my tank at the moment, but if I add them, these will have to be stocked often to keep a population of them.
Here are a couple videos of my tank.
The first one pretty much follows the largest blenny of the tank:
I tried to view the tank in general with this video, bouncing from one fish to another:
Below is a video of one of the crabs...do you all agree with my ID? If not, please help me ID this crab. Thanks!
We discovered a new critter in my 20g long tank. After feeding some frozen brine shrimp, my daughter noticed a worm-like creature, a little over an inch long, swimming around the glass in the front right corner of the tank, about mid depth. At first, I thought it was a chunk of dead sea grass caught in a current eddy, but nope... Upon closer inspection, it was brownish and had a segmented body, with 2 long antennae or head appendages, and a bunch of legs. It resembled a centipede, so I assumed it was some sort of isopod. It was too fast to get a picture. By the time that I had my phone at the ready, it had scurried back into the oyster reef. It was pretty cool.
Of course, I had some concern about the potential for parasitism, even though I thought it was probably OK (because if it was a fish parasite, then it would have a host by now especially since it was over an inch long). Anyway, I thought it was pretty cool but it freaked the heck out of my daughter.
After researching on-line, it looks a lot like the on-line pictures of the elongated eelgrass isopod, Erichsonella attenuata. This species, if correctly ID'd, is not a threat for parasitic activity.
I will try and get pics and see if anyone can confirm the ID.
Thanks Gerald. I haven't seen it since. I really want to photograph or video, and ID it. But most of all, I want to observe it and learn more about it. Very interesting about the chemical defenses. When it was out, the fish ignored it.
I'm not 100% certain on the ID, although the Erichsonella attenuata pictures seem to best represent my memory. The only thing that gives me pause is that maximum sizes depicted on the web indicate about an 18 mm max. This creature was easily double that.
I'd love to also find some skeleton shrimp and see how they do in the tank. We're going collecting again tomorrow. Can't wait!