Chesapeake Bay Oyster Reef Biotope Tank

Chasmodes · Sep 30, 2017

Here's another video of my daughter feeding the fish last night. After the chopped clams were devoured, they skilletfish didn't want to leave her hand!

I'm not sure what's going on with the large killifish. A white spot showed up the other day on its side. Yesterday, it looked a little better and today even better. Perhaps its own immune system is fighting it off? If not, I'd have to find a way to trap that fish and provide treatment.

Chasmodes · Oct 1, 2017

The naked gobies are exhibiting more color than I thought that they ever would. Some of their fins are trimmed with yellow or red (depending on how the light hits them) and also they get dark and the lighter areas between their color bands get bold white dorsally. Also, in these videos, it's easy to see the difference between the male and female blennies. The males have a blue spot on the front of their dorsal fin.

I figured out a way to get the fish to almost figure out that I'm not there. I need to build a canopy for my lights. For now, the cardboard box that my glass tank top came in fits perfectly as a temporary solution, placed there when I view the fish and removed when I'm done. I'll try and get a non-feeding video today and post it here. The fish tend to settle down and do their thing after feeding time is over, somewhat. They forage, get into territorial disputes, asserting dominance and challenging the pecking order, moving from one oyster shell refuge to another, chasing opponents...and looking for me.

But for now, here's another feeding video. This video is amusing because the fish steal the food away from my daughter twice:

Chasmodes · Oct 5, 2017

Not so good update of the 20g high... The tunicate and barnacle died. I'm bummed, but I expected that to happen. The fish are doing well for the most part. The largest killie still shows a spot on its side, but other than that, seems healthy and eating well, with no sign of distress. Both killies looked great until last night when I noticed that them and a few gobies had beat up tails. I watched them for about an hour after feeding to see who the culprit was, but still don't know. They all pick on each other a bit... blennies chase blennies, gobies chase gobies, killies chase killies, skilletfish chase anyone away from their hiding spot, and they all chase each other a little bit. But, none of them seem to do much damage. Well, except for the smallest blenny. I caught it biting a gobies tail, latching on hard and with a ripping motion. So, maybe I found the culprit. None of the fish go into hiding or seem stressed, so I hope everyone heals and moves about their daily routine.

The grass shrimp numbers are declining. Other than a couple carpet surfers, most of them probably were prey to the fish, although I didn't witness any predation. The crabs are a different story. I never see them, although I know that they are there, because they leave behind their molted shells. I'll have to check the tank at night to see what is going on. I still haven't done that.

I figured out a way to get them to behave naturally and not beg for food. Feed them. Duh...!!! But, that alone doesn't work because no matter how fat they are, they still beg for more. So, I set up my temporary "canopy" and also set up a DIY blind using shop clamps, a towel, a bungee cord and a hanger. After a couple minutes, they forget that I'm there. In the video linked below, you can see them acting more naturally. That is, until one of them spotted me moving at the end. Also, in the video, I came to realize that my killies might be a pair. Maybe some spawning activity? Hope y'all like it:

Chasmodes · Oct 10, 2017

Update: In my 20g high, the largest blenny, that I thought was a female, revealed the blue spot on his dorsal fin, finally. The spot is hidden with a dark border, but when the light hits it right, it glows. That fish doesn't flare his dorsal fin much, at least until recently. He's king of the tank. The next largest blenny doesn't seem to have a spot, so I think that one is a female. The second biggest one doesn't really flare the dorsal too much, so it is hard to tell if a spot is there. The base coloration is totally different than the larger one. Although, there is a bunch of variation between all of the individual specimens. There is another small female, and the rest are males as they display their bright blue spots all the time. None of the blennies have shown any spawning behavior yet. They're pigs. All they want to do is eat. That said, the largest blenny seems to finally hang around one particular oyster shell for long periods, defending it. But, often abandons it in search of food. He chases all fish away from that shell, but it's hard to tell if it is because he is defending the shell, or just showing them all that he is the boss.

As far as the Ulva in the tank goes, it's doing well. I feed these fish heavily, so there are plenty of nutrients in this tank. That might explain why the sea squirt and barnacle expired. I don't think it was for lack of food, at least this time. I also moved them so I could observe them, possibly upsetting their environmental needs. They were alive and well before I intervened. I performed a water change after testing the water. There was a trace amount of ammonia, some nitrates and 50 ppm or so of nitrates. Out of about 30 grass shrimp in this tank, only about 10 remain at most, maybe less. I think the missing ones have been eaten. A couple jumped out of the tank. The grass shrimp in this tank hide a lot in the Ulva and Gracilaria, for obvious reasons, so it's tough to get a count. In the 20g long, where there are subadults and juvenile fish, the grass shrimp are always out and about.

It's tough to tell what sex the fish are in the 20g long as those fish don't seem to have any spot on the dorsal, but they're still a big small, I think. Maybe they haven't developed that coloration yet? A friend of mine who is an expert on Chasmodes says that they develop the spot early in life. If that is true, then my 20g long most likely the fish in that tank are all female. I performed a water change and cleaned out a bunch of cyano. Water parameters were zero for ammonia and nitrite, 30 ppm for nitrates. There are at least 8 grass shrimp out of about a dozen that I placed in there. I know of one jumper, the others may have been eaten.

The killifish seem to do a courtship wiggle or dance often. I don't know if they've deposited eggs or not. I haven't seen it happen nor have I seen any on the vegetation, although with the appetite of those fish, I doubt they'd last long enough for me to see them.

Chasmodes · Oct 10, 2017

More observations:

I learn something about their behavior each day. I had some doubts about keeping this many benthic species in a limited environment (even 100 gallons). But, what I've learned are the following:

- If the fish can handle the nutrient load of feeding them, then they seem to "get along" just fine. They do chase each other, even a little fin nipping. But, the picked on seem to heal up fast, and sometimes fight back. After they get chased, they don't hide in a corner of the tank or behind a filter, they go about as if nothing happened. This is true for all of the species in the tank.

- After my last collecting trip, all of the blennies and gobies came from one oyster box that is smaller than my 20 gallon tank. I'd say that they can get along just fine in a small tank environment based on that alone. I read so many posts about people worried about multiple blennies in a tank. I suspect that it depends on each species, but these are pretty aggressive carnivorous blennies, and with enough specimens to "spread the love", nobody gets picked on more than the others.

- Lots of hiding spots is the key, including good escape routes. These escape routes can be crevices in rock (in my case, between oysters in the cultch), through a mat of macroalgae, or within a hiding spot.

- Sometimes when a blenny gets chased, it simply spins does a lap around an oyster shell enough times that the fish doing the chasing either gives up or loses interest.

- Skilletfish are fearless. But, I'd say that all of them are not really afraid of each other.

- I was worried about mud crabs being a threat to the fish. After watching them around the fish, I no longer fear that as an issue. Blennies, gobies and skilletfish often land on them with no reaction from the crab, except sometimes they shoo the fish away with a claw, but do not try to pinch the fish.

- Grass shrimp live much longer in these tanks than I ever imagined. I thought that they'd be all eaten within a week. I'm pleased about that.

Breadman03 · Oct 16, 2017

This made me think of your reef.

Chasmodes · Oct 16, 2017

Very cool! Maybe one day I'll have a system that can support them

Paul B · Oct 16, 2017

I love this tank Chas. I also have an unlimited supply of mussels.

Chasmodes · Oct 16, 2017

Thanks Paul! That's quite a cluster of mussels! That would be a nice centerpiece for a native tank

Paul B · Oct 16, 2017

Unfortunately I am moving before next summer so I am leaving my tidal pond where I collect for new pastures. I hope I can find some nice tide pool in the Peconic.

Chasmodes · Oct 17, 2017

Just looking at Google Maps, it looks like there are some pretty promising spots!

Chasmodes · Oct 17, 2017

Quick update:

Both tanks seem to have an increase in itching/scratching behavior. I don't see any visible parasites, but that doesn't mean they aren't there. It's hard to get a good look at them anyway because they move around so much. In fact, I'd say that there likely have been parasites in these tanks all along. All of the fish have scratched a little since the beginning. It's just more frequent now. So, what to do.

My assumption is that the culprit is Cryptocaryon irritans simply because freshwater ich doesn't seem to tolerate any salinity. From what I've read, C. irritans doesn't care for freshwater, so my initial plan is to reduce the salinity and perform a long term hyposalinity treatment.

Currently, the sg is 1.016. I plan to reduce it to about 1.009 and keep it that way for several weeks for each tank. I'd like to have these fish healthy by the time I get the big tank set up.

These fish are very hardy, so I don't anticipate any problems. The shrimp should be OK, as they are commonly caught at a lesser salinity than what I'm doing. My guess is that the mud crabs will be OK too, but I'm not 100% sure. I doubt the Ulva will make it through the process, but we will see.

Chasmodes · Oct 19, 2017

Last night, I dropped the sg from 1.015 to 1.010. The fish behavior changed big time in many ways. First, all of the blennies and gobies went into hiding, including one blenny that spent the night against the glass at the filter intake. All of the other blennies hid in oyster shells. The skilletfish either hid or stuck to the glass, not much different than before. The killifish pretty much behaved the same and even kept feeding.

I think that it had an immediate effect on the parasites, maybe not killing them, but agitating them because all of the fish scratched even more than before (and that was a lot of scratching before).

This morning, nothing changed, all of the fish still hiding and the killies doing the same thing. I was a bit concerned about dropping it too fast that I might have hurt the fish. So, this morning, I tried to feed them thinking that if they perked up and ate, all should be OK, and if not...not sure what I'd do.

So, I fed them a block of frozen mysid shrimp. All of the fish perked up and ate, and many of them took the food right from my hand. They foraged a bit and then they went back to hiding.

The grass shrimp seem unaffected.

So, I'll continue at this sg for a week and I might drop it one more point if all goes well.

Chasmodes · Oct 19, 2017

Also, their behavior may explain why I had a hard time catching blennies at one of my spots where I found plenty of them a week earlier (and a week later). We had a lot of rain that week. I always thought that they just went to deeper water (followed the salt wedge), but I bet that all they do is hunker down in their oyster shells or other cover.

Chasmodes · Nov 1, 2017

Well, the hypo treatment was a disaster, either that or the disease was far more advanced than I ever thought. I still am not sure what the disease was. Based on the fish behavior during their downfall, it could have been ich, velvet or flukes. I never saw visible signs of the disease (no white spots, lesions, film, or cysts), but that doesn't mean that they didn't exist. Those fish moved around a lot and it was difficult to observe them. At first, they scratched a little bit, then a lot by the time that I started hypo. Every fish in the tank did this, and frequently.

After a day or two following the salinity drop, the blennies started swimming near the surface near the glass, as if to be near the surface or to escape. Their breathing was more rapid than normal, but I wasn't sure if it was due to the infestation or the constant swimming (these blennies lack a swim bladder). The skilletfish also clung to the glass near the surface. The gobies did also, but not as much. All of the blennies, gobies and killifish continued to scratch, the skilletfish didn't scratch though. Eventually, they started dying, one by one. The blennies died off first, followed by the skilletfish, and then the gobies. I thought that the treatment killed them at first, but the more that I read about these diseases, the more it seems possible that the disease killed them all. I guess it is possible that either the salinity drop or a pH change could have shocked them enough that their immune systems were compromised. I don't know what the disease was to this day. They went from acting very strong and healthy to dead within a week, and three to five days of hypo. I was pretty depressed about it, that's why I didn't post what happened. But, maybe others will learn from this as I progress and learn too. It is tough for me to go in and watch this tank. The killifish don't interest me that much, but I owe it to them to do my best for them.

The 20g high fish inhabitants are down to the 2 mummichogs, at least one mud crab, and about a dozen grass shrimp. The mummichogs don't scratch any longer, but they do at times shake in place, but rarely. The SG is currently at 1.012, slowly raised in the last week from 1.008. I plan to drop it back down to 1.008 and keep it there. From that point on, it will be my QT tank prior to introducing fish to the larger tank. If the killifish surive this, then they'll go in the display. If not, then I can also keep the tank fallow since I probably won't collect any more fish until next spring or summer.

The 20g long is doing great, as are the fish. These fish do not scratch at all. Cyano seems to be dying back a little each day. My dilemma is what to do about this tank in preparation of the larger tank set up, because everything is going into the main tank. I believe in the hypo treatment, but am a little gun shy after what happened with the 20g high. If I do the hypo treatment in this tank, it will be done slow and carefully, watching pH closely too. Right now, I use a floating hydrometer. I also have one with the swinging arm. But, I'm considering purchasing a refractometer...rather, I plan on purchasing one. I won't continue until I do.

It's fascinating watching the fish totally ignore the mud crabs. They sit right next to them, land on them, sit on them, look at them, and the crabs do nothing in response. Once in a while, they'll raise their pincers a bit, but don't pinch, as if to shoo the fish away. More often, the crabs retreat to their hiding spots especially if the fish approach rapidly. The crabs seemed to stick to their hiding spots for longer periods of time.

These fish are still sub-adults or juveniles. They feed from my hand, but at the same time, they're very spooky and always on edge. The blennies move all around the structure, and when they do, they're always tight to the cover. When out in the open, if they're not feeding, then they don't stay there long. But, they don't sit and hide all the time, they're always on the move. Some of them have favorite hiding and perching spots, but they don't seem to be married to them. The blennies are the most assertive species in the tank, not fearing the other fish. They're more spooky about my presence. I kind of like that, because they tend to act normally except for at feeding time.

The gobies tend to hide and stick their heads out often, but aren't shy about being in the open. They can be skittish, but not quite like the blennies. They can be aggressive, and will chase anything away, but they are often chased more by the blennies than they other way around. The blennies sort of see them as a nuisance rather than fear them.

The skilletfish hide the most, but, they move around a lot too, most always attached to a shell or the glass, but sometimes hug the bottom, especially at feeding time.

4 out of the 6 blennies in the tank will take food from my hand. The other two, the smallest, sit on one side of the tank and wait for the current to bring their meals to them. 3 of the 6 skilletfish will take food from my hand, the others hunt food down or hang out near the 2 blennies. The gobies will sometimes take food from my hand, but the other fish chase them away. If they were the only species in there, then all of them would do it. The skilletfish stick to my hand when they feed, but they get territorial, and chase the blennies and gobies away as well as competing skilletfish. The blennies come right back though.

All of the fish mistake my hand for food at times and bite. The blennies tend to peck, but can bite a bit hard. The gobies put a lot of effort into biting and the bite is strong, but their teeth are much smaller, so don't grab much. The skilletfish have larger mouths and stronger jaws, and hence, the stronger bite, especially if they get ahold of a fold of skin. None of the bites hurt, but it is a good way to get to know the capabilities of your fish. I don't recommend testing triggerfish though

Jeremy K.A. · Nov 8, 2017

Is this a cold water aquarium?

Paul B · Nov 8, 2017

I would think it's a room temperature aquarium without a heater.

tj w · Nov 8, 2017

1.015 to 1.010 seems like a quick drop for one day, but you never know. I’m sorry for your losses, I absolutely enjoy this thread and will continue to follow.

Chasmodes · Nov 9, 2017

Jeremy, Paul is correct. I keep the tank at room temperature. Right now, I have no plans for a chiller, but I won't rule it out. I want to see how much the low temps get during the winter since we don't keep the heat on in the rec room. Our furnace is in the basement, which keeps that room a bit warmer, and that is where the sump will be.

Thanks tj w. My plan in the future for doing hypo treatment, and I'm not going to give up on it, is to do it gradually over the course of a week (as prevention). These fish should be used to large swings in salinity simply because they were caught in an area where the max SG is 1.014, and it fluctuates from month to month. But, you're right, 5 points seems extreme to me, where 2 or 3 should be tolerable and something that they deal with in the wild from time to time.

The 20g tank is doing great. All of the fish are growing and seem healthy, and no scratching, thank goodness. They all eat like pigs.