Zebra loaches and Cory cats

[awoods]

Hi! I'm Amy and I'm new to the forum. I have an issue with zebra loaches and cory cats in 2 tanks. One is a 55 gal, the other is a 37 gal. Excellent filtration, 0 ammonia in both. 30 - 50% water change weekly to biweekly. Both had a large number of small snails, which I took advantage of by feeding snails to a green-spotted pufferfish (brackish 30 gal tank). The original puffer gobbled up as many snails as I could give so number of snails was never an issue. When he died (eight years old) we got a second puffer, expecting to continue our transfer of snails from the other 2 tanks. This guy didn't have the appetite for snails as the previous puffer, so suddenly snails became a problem. Somewhere (I can't remember where now) I got the idea of loaches as a solution to the snail problem. After some research to see if loaches were OK with our fish, we got zebra loaches. We got 3 for the 55 gal tank (20 cardinals, 1 large pleco-13 years old, and asst corys) and 3 for the 37 gal tank (nothing but zebras and 4 angelfish). Had no issues or problems with the existing fish for over a year, other than one of the loaches in the larger tank died suddenly a few months ago. So now there are only 2 in the 55-gal, 3 in the 37-gal. However, we recently added 3 baby cory cats to the freshwater tanks to help with clean-up. Initially the 3 in the angelfish tank all were found dead on the same day. My husband suggesed that the angels "whacked" the corys. When the corys in the tetra tank died, he then blamed the loaches in their deaths. After online research, esp. this forum, I do not think the loaches killed the corys. I think the problem is with the corys at the LFS. I need suggestions as he wants to just get the loaches out of the tanks. I want to move the 2 from 55 gal in with the 3 in the other tank, for a shoal of 5. Then need to change substrate in that tank to a more loach-friendly sandy bottom. Major problem so far is that I haven't been able to catch the 2 in the larger tank! Any suggestions, regarding loaches killing corys and how to get the 2 moved in with the 3? Thanks, and I love your forum!

[Diana]

I have kept a wide range of Loaches and Cories in the same tanks and have never had a problem with Loaches attacking Cories or Angel Fish. Over the years the Cory population has dropped, but they never were attacked. Old age, I think. Here are a few combos:

Clown Loaches (young ones, about 3" long) are in a tank right now with an adult Angel and several other fish. The Loaches play around mostly near the bottom, and the Angel has found the low-flow areas of the tank near the top. I think there is one Cory in there, and several Bristlenose Cats. I got these guys when they were under 2" long, and they have grown really fast. (Clown Loaches did not bother them, even when they were little) The Loaches do not bother any of the fish in this tank. Mostly they just hang out with each other.

B. kubotai with several cats including Rineloricaria and a lone Cory. There is at least one sidthemunki in this tank, too. Larger fish include Rainbows and Clown Barbs.

Sidthemunkis with some Shell Dwelling Cichlids, and 2 Loricariads; one Peckoltia and one Pleco that is not a common, but is pretty large. (Moved to the next tank)

Dojo Loach with Roseline Barbs, an Oto and the Plec from the previous set up. There is an Oto in this tank, too.

Clown Loaches, Bichers and some others with Corydorus barbatus. The Bichers chased the Cories out of this tank, I found them in the sump. Bichers are predatory fish, and will eat any other fish that fits in their mouth, and they have big mouths.

Kuhlie Loaches with Guppies and Bronze Cories. I think the Bronze Cories are past breeding age, but they are parents and some of the offspring.

B. striata with Endlers Livebearers. Maybe the Zebra Loaches were eating Endler's fry, but they never bothered the adults.

The only Loach vs Angel problem was the other way around: The Angels defended their nest, eggs and fry against all comers, and the Loaches (sids) just went and hid under the substrate. I had to take down that whole tank to find the little guys.

The only Loaches that I have had chase the other fish were Skunk Loaches. I have heard that Tiger Loaches (Synocrossus) can be pretty aggressive, too.
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Other issues:
New fish, any species, needs to be quarantined, and treated for whatever parasite or disease shows up before they are placed in the display tank. SOme species are known for carrying certain diseases or parasites, so treating for that is usually done, even if the fish show no symptoms. Many bottom feeders (Cats, Loaches, others) can pick up internal parasites quite easily, and if you do not quarantine and treat for worms these can get passed along to the fish in the main tank.

No matter how nice a species is in general, there is always a range of behavior, and one individual fish might be uncharacteristically aggressive. Loaches, Cichlids and Bettas are the fish that are most often thought of when anyone mentions the idea, "But each fish is different, watch them..."